From 2c82e31a29263d550857b30f2c91103804f1183c Mon Sep 17 00:00:00 2001
From: Revone <zrwusa@gmail.com>
Date: Sun, 20 Aug 2023 18:52:57 +0800
Subject: [PATCH] Optimize the insertAfter method of SinglyLinkedList,
 insertAfter, insertBefore, and delete methods of DoublyLinkedList to directly
 add an element after a given node's reference without the need for traversal.
 And conducted performance test.

Modify the insertBefore and delete methods of SinglyLinkedList to align their method APIs with those of DoublyLinkedList.
---
 .../binary-tree/binary-indexed-tree.ts        |   2 +-
 .../linked-list/doubly-linked-list.ts         | 102 +++++++++++-------
 src/data-structures/linked-list/index.ts      |   1 +
 .../linked-list/singly-linked-list.ts         |  75 ++++++++-----
 .../linked-list/skip-linked-list.ts           |   3 +-
 src/data-structures/matrix/matrix2d.ts        |  26 ++---
 src/data-structures/matrix/vector2d.ts        |  50 ++++-----
 tests/unit/data-structures/constants/index.ts |   1 +
 .../data-structures/constants/magnitude.ts    |  11 ++
 .../linked-list/doubly-linked-list.test.ts    |  18 ++--
 .../unit/data-structures/linked-list/index.ts |   2 +
 .../linked-list/linked-list.test.ts           |  37 +++++++
 .../linked-list/singly-linked-list.test.ts    |  16 +--
 ...inked-list.ts => skip-linked-list.test.ts} |   6 +-
 .../priority-queue/max-priority-queue.test.ts |   8 +-
 15 files changed, 228 insertions(+), 130 deletions(-)
 create mode 100644 tests/unit/data-structures/constants/index.ts
 create mode 100644 tests/unit/data-structures/constants/magnitude.ts
 create mode 100644 tests/unit/data-structures/linked-list/linked-list.test.ts
 rename tests/unit/data-structures/linked-list/{skip-linked-list.ts => skip-linked-list.test.ts} (60%)

diff --git a/src/data-structures/binary-tree/binary-indexed-tree.ts b/src/data-structures/binary-tree/binary-indexed-tree.ts
index 15e7e20..56880ce 100644
--- a/src/data-structures/binary-tree/binary-indexed-tree.ts
+++ b/src/data-structures/binary-tree/binary-indexed-tree.ts
@@ -61,7 +61,7 @@ export class BinaryIndexedTree {
      * the sum.
      * @returns the sum of the elements in the range specified by the start and end indices.
      */
-    public getRangeSum(start: number, end: number): number {
+    getRangeSum(start: number, end: number): number {
         if (!(0 <= start && start <= end && end <= this._sumTree.length))
             throw 'Index out of bounds';
         return this.getPrefixSum(end) - this.getPrefixSum(start);
diff --git a/src/data-structures/linked-list/doubly-linked-list.ts b/src/data-structures/linked-list/doubly-linked-list.ts
index 72435c6..d5ad36f 100644
--- a/src/data-structures/linked-list/doubly-linked-list.ts
+++ b/src/data-structures/linked-list/doubly-linked-list.ts
@@ -243,7 +243,7 @@ export class DoublyLinkedList<T> {
      * @returns The `insert` method returns a boolean value. It returns `true` if the insertion is successful, and `false`
      * if the index is out of bounds.
      */
-    insert(index: number, val: T): boolean {
+    insertAt(index: number, val: T): boolean {
         if (index < 0 || index > this.length) return false;
         if (index === 0) {
             this.unshift(val);
@@ -286,30 +286,37 @@ export class DoublyLinkedList<T> {
         return removedNode!.val;
     }
 
+    delete(valOrNode: T): boolean;
+    delete(valOrNode: DoublyLinkedListNode<T>): boolean;
     /**
-     * The `delete` function removes a node with a specific value from a doubly linked list.
-     * @param {T} val - The `val` parameter represents the value that you want to delete from the linked list.
-     * @returns The `delete` method returns a boolean value. It returns `true` if the value `val` is found and deleted from
-     * the linked list, and `false` if the value is not found in the linked list.
+     * The `delete` function removes a node from a doubly linked list based on either the node itself or its value.
+     * @param {T | DoublyLinkedListNode<T>} valOrNode - The `valOrNode` parameter can accept either a value of type `T` or
+     * a `DoublyLinkedListNode<T>` object.
+     * @returns The `delete` method returns a boolean value. It returns `true` if the value or node was successfully
+     * deleted from the doubly linked list, and `false` if the value or node was not found in the list.
      */
-    delete(val: T): boolean {
-        let current = this.head;
-        while (current) {
-            if (current.val === val) {
-                if (current === this.head) {
-                    this.shift();
-                } else if (current === this.tail) {
-                    this.pop();
-                } else {
-                    const prevNode = current.prev;
-                    const nextNode = current.next;
-                    prevNode!.next = nextNode;
-                    nextNode!.prev = prevNode;
-                    this.length--;
-                }
-                return true;
+    delete(valOrNode: T | DoublyLinkedListNode<T>): boolean {
+        let node: DoublyLinkedListNode<T> | null;
+
+        if (valOrNode instanceof DoublyLinkedListNode<T>) {
+            node = valOrNode;
+        } else {
+            node = this.findNode(valOrNode);
+        }
+
+        if (node) {
+            if (node === this.head) {
+                this.shift();
+            } else if (node === this.tail) {
+                this.pop();
+            } else {
+                const prevNode = node.prev;
+                const nextNode = node.next;
+                prevNode!.next = nextNode;
+                nextNode!.prev = prevNode;
+                this.length--;
             }
-            current = current.next;
+            return true;
         }
         return false;
     }
@@ -494,16 +501,25 @@ export class DoublyLinkedList<T> {
         return accumulator;
     }
 
+    insertAfter(existingValueOrNode: T, newValue: T): boolean;
+    insertAfter(existingValueOrNode: DoublyLinkedListNode<T>, newValue: T): boolean;
     /**
-     * The function inserts a new value after an existing value in a doubly linked list.
-     * @param {T} existingValue - The existing value is the value of the node after which we want to insert the new value.
-     * @param {T} newValue - The `newValue` parameter represents the value of the new node that you want to insert after
-     * the existing node.
-     * @returns The method is returning a boolean value. It returns true if the insertion is successful and false if the
-     * existing value is not found in the linked list.
+     * The `insertAfter` function inserts a new node with a given value after an existing node in a doubly linked list.
+     * @param {T | DoublyLinkedListNode<T>} existingValueOrNode - The existing value or node in the doubly linked list
+     * after which the new value will be inserted. It can be either the value of the existing node or the existing node
+     * itself.
+     * @param {T} newValue - The value that you want to insert into the doubly linked list.
+     * @returns The method returns a boolean value. It returns true if the insertion is successful, and false if the
+     * existing value or node is not found in the doubly linked list.
      */
-    insertAfter(existingValue: T, newValue: T): boolean {
-        const existingNode = this.findNode(existingValue);
+    insertAfter(existingValueOrNode: T | DoublyLinkedListNode<T>, newValue: T): boolean {
+        let existingNode;
+
+        if (existingValueOrNode instanceof DoublyLinkedListNode<T>) {
+            existingNode = existingValueOrNode;
+        } else {
+            existingNode = this.findNode(existingValueOrNode);
+        }
 
         if (existingNode) {
             const newNode = new DoublyLinkedListNode(newValue);
@@ -523,16 +539,26 @@ export class DoublyLinkedList<T> {
         return false;
     }
 
+    insertBefore(existingValueOrNode: T, newValue: T): boolean;
+    insertBefore(existingValueOrNode: DoublyLinkedListNode<T>, newValue: T): boolean;
     /**
-     * The `insertBefore` function inserts a new value before an existing value in a doubly linked list.
-     * @param {T} existingValue - The existing value is the value of the node that you want to insert the new value before.
-     * @param {T} newValue - The `newValue` parameter represents the value of the new node that you want to insert before
-     * the existing node.
-     * @returns The method is returning a boolean value. It returns true if the insertion is successful and false if the
-     * existing value is not found in the linked list.
+     * The `insertBefore` function inserts a new value before an existing value or node in a doubly linked list.
+     * @param {T | DoublyLinkedListNode<T>} existingValueOrNode - The existing value or node in the doubly linked list
+     * before which the new value will be inserted. It can be either the value of the existing node or the existing node
+     * itself.
+     * @param {T} newValue - The `newValue` parameter represents the value that you want to insert into the doubly linked
+     * list.
+     * @returns The method returns a boolean value. It returns `true` if the insertion is successful, and `false` if the
+     * insertion fails.
      */
-    insertBefore(existingValue: T, newValue: T): boolean {
-        const existingNode = this.findNode(existingValue);
+    insertBefore(existingValueOrNode: T | DoublyLinkedListNode<T>, newValue: T): boolean {
+        let existingNode;
+
+        if (existingValueOrNode instanceof DoublyLinkedListNode<T>) {
+            existingNode = existingValueOrNode;
+        } else {
+            existingNode = this.findNode(existingValueOrNode);
+        }
 
         if (existingNode) {
             const newNode = new DoublyLinkedListNode(newValue);
diff --git a/src/data-structures/linked-list/index.ts b/src/data-structures/linked-list/index.ts
index 0bdd0b6..e489ecc 100644
--- a/src/data-structures/linked-list/index.ts
+++ b/src/data-structures/linked-list/index.ts
@@ -1,2 +1,3 @@
 export * from './singly-linked-list';
 export * from './doubly-linked-list';
+export * from './skip-linked-list';
diff --git a/src/data-structures/linked-list/singly-linked-list.ts b/src/data-structures/linked-list/singly-linked-list.ts
index 1595df0..7f2805b 100644
--- a/src/data-structures/linked-list/singly-linked-list.ts
+++ b/src/data-structures/linked-list/singly-linked-list.ts
@@ -220,17 +220,23 @@ export class SinglyLinkedList<T> {
         return removedNode!.val;
     }
 
+    delete(valueOrNode: T): boolean;
+    delete(valueOrNode: SinglyLinkedListNode<T>): boolean;
     /**
-     * The `delete` function removes a specified value from a linked list and returns true if the value was found and
-     * removed, otherwise it returns false.
-     * @param {T} value - The value parameter represents the value of the node that needs to be deleted from the linked
-     * list.
-     * @returns The `delete` method returns a boolean value. It returns `true` if the value was successfully deleted from
-     * the linked list, and `false` if the value was not found in the linked list.
+     * The delete function removes a node with a specific value from a singly linked list.
+     * @param {T | SinglyLinkedListNode<T>} valueOrNode - The `valueOrNode` parameter can accept either a value of type `T`
+     * or a `SinglyLinkedListNode<T>` object.
+     * @returns The `delete` method returns a boolean value. It returns `true` if the value or node is found and
+     * successfully deleted from the linked list, and `false` if the value or node is not found in the linked list.
      */
-    delete(value: T): boolean {
-        let current = this.head;
-        let prev = null;
+    delete(valueOrNode: T | SinglyLinkedListNode<T>): boolean {
+        let value: T;
+        if (valueOrNode instanceof SinglyLinkedListNode<T>) {
+            value = valueOrNode.val;
+        } else {
+            value = valueOrNode;
+        }
+        let current = this.head, prev = null;
 
         while (current) {
             if (current.val === value) {
@@ -256,7 +262,7 @@ export class SinglyLinkedList<T> {
     }
 
     /**
-     * The `insert` function inserts a value at a specified index in a singly linked list.
+     * The `insertAt` function inserts a value at a specified index in a singly linked list.
      * @param {number} index - The index parameter represents the position at which the new value should be inserted in the
      * linked list. It is of type number.
      * @param {T} val - The `val` parameter represents the value that you want to insert into the linked list at the
@@ -264,7 +270,7 @@ export class SinglyLinkedList<T> {
      * @returns The `insert` method returns a boolean value. It returns `true` if the insertion is successful, and `false`
      * if the index is out of bounds.
      */
-    insert(index: number, val: T): boolean {
+    insertAt(index: number, val: T): boolean {
         if (index < 0 || index > this.length) return false;
         if (index === 0) {
             this.unshift(val);
@@ -395,20 +401,25 @@ export class SinglyLinkedList<T> {
         return null;
     }
 
+    insertBefore(existingValue: T, newValue: T): boolean
+    insertBefore(existingValue: SinglyLinkedListNode<T>, newValue: T): boolean
     /**
      * The `insertBefore` function inserts a new value before an existing value in a singly linked list.
-     * @param {T} existingValue - The existing value is the value that already exists in the linked list and before which
-     * we want to insert a new value.
+     * @param {T | SinglyLinkedListNode<T>} existingValueOrNode - The existing value or node that you want to insert the
+     * new value before. It can be either the value itself or a node containing the value in the linked list.
      * @param {T} newValue - The `newValue` parameter represents the value that you want to insert into the linked list.
-     * @returns The `insertBefore` function returns a boolean value. It returns `true` if the `newValue` is successfully
-     * inserted before the first occurrence of `existingValue` in the linked list. It returns `false` if the
-     * `existingValue` is not found in the linked list.
+     * @returns The method `insertBefore` returns a boolean value. It returns `true` if the new value was successfully
+     * inserted before the existing value, and `false` otherwise.
      */
-    insertBefore(existingValue: T, newValue: T): boolean {
-        if (!this.head) {
-            return false;
-        }
+    insertBefore(existingValueOrNode: T | SinglyLinkedListNode<T>, newValue: T): boolean {
+        if (!this.head) return false;
 
+        let existingValue: T;
+        if (existingValueOrNode instanceof SinglyLinkedListNode<T>) {
+            existingValue = existingValueOrNode.val;
+        } else {
+            existingValue = existingValueOrNode;
+        }
         if (this.head.val === existingValue) {
             this.unshift(newValue);
             return true;
@@ -429,16 +440,24 @@ export class SinglyLinkedList<T> {
         return false;
     }
 
+    insertAfter(existingValueOrNode: T, newValue: T): boolean
+    insertAfter(existingValueOrNode: SinglyLinkedListNode<T>, newValue: T): boolean
     /**
-     * The function inserts a new value after an existing value in a singly linked list.
-     * @param {T} existingValue - The existing value is the value of the node after which we want to insert the new value.
-     * @param {T} newValue - The `newValue` parameter represents the value that you want to insert into the linked list
-     * after the node with the `existingValue`.
-     * @returns The method is returning a boolean value. It returns true if the insertion is successful and false if the
-     * existing value is not found in the linked list.
+     * The `insertAfter` function inserts a new node with a given value after an existing node in a singly linked list.
+     * @param {T | SinglyLinkedListNode<T>} existingValueOrNode - The existing value or node in the linked list after which
+     * the new value will be inserted. It can be either the value of the existing node or the existing node itself.
+     * @param {T} newValue - The value that you want to insert into the linked list after the existing value or node.
+     * @returns The method returns a boolean value. It returns true if the new value was successfully inserted after the
+     * existing value or node, and false if the existing value or node was not found in the linked list.
      */
-    insertAfter(existingValue: T, newValue: T): boolean {
-        const existingNode = this.findNode(existingValue);
+    insertAfter(existingValueOrNode: T | SinglyLinkedListNode<T>, newValue: T): boolean {
+        let existingNode: T | SinglyLinkedListNode<T> | null;
+
+        if (existingValueOrNode instanceof SinglyLinkedListNode) {
+            existingNode = existingValueOrNode;
+        } else {
+            existingNode = this.findNode(existingValueOrNode);
+        }
 
         if (existingNode) {
             const newNode = new SinglyLinkedListNode(newValue);
diff --git a/src/data-structures/linked-list/skip-linked-list.ts b/src/data-structures/linked-list/skip-linked-list.ts
index 693da49..9d79cfe 100644
--- a/src/data-structures/linked-list/skip-linked-list.ts
+++ b/src/data-structures/linked-list/skip-linked-list.ts
@@ -1 +1,2 @@
-export {}
\ No newline at end of file
+export class SkipLinkedList {
+}
\ No newline at end of file
diff --git a/src/data-structures/matrix/matrix2d.ts b/src/data-structures/matrix/matrix2d.ts
index 1a5a7a4..d07a291 100644
--- a/src/data-structures/matrix/matrix2d.ts
+++ b/src/data-structures/matrix/matrix2d.ts
@@ -33,7 +33,7 @@ export class Matrix2D {
      * The function returns a 2D array with three empty arrays.
      * @returns An empty 2-dimensional array with 3 empty arrays inside.
      */
-    public static get empty(): number[][] {
+    static get empty(): number[][] {
         return [[], [], []]
     }
 
@@ -41,7 +41,7 @@ export class Matrix2D {
      * The above function returns a 3x3 identity matrix.
      * @returns The method is returning a 2-dimensional array of numbers representing the identity matrix.
      */
-    public static get identity(): number[][] {
+    static get identity(): number[][] {
         return [
             [1, 0, 0],
             [0, 1, 0],
@@ -53,7 +53,7 @@ export class Matrix2D {
      * @returns The getter method is returning the value of the private variable `_matrix`, which is a two-dimensional
      * array of numbers.
      */
-    public get m(): number[][] {
+    get m(): number[][] {
         return this._matrix
     }
 
@@ -63,7 +63,7 @@ export class Matrix2D {
      * @returns A new instance of the Vector2D class is being returned. The values of the returned vector are taken from
      * the first column of the matrix.
      */
-    public get toVector(): Vector2D {
+    get toVector(): Vector2D {
         return new Vector2D(this._matrix[0][0], this._matrix[1][0])
     }
 
@@ -73,7 +73,7 @@ export class Matrix2D {
      * @param {Matrix2D} matrix2 - The parameter `matrix2` is a Matrix2D object.
      * @returns a new instance of the Matrix2D class, which is created using the result array.
      */
-    public static add(matrix1: Matrix2D, matrix2: Matrix2D): Matrix2D {
+    static add(matrix1: Matrix2D, matrix2: Matrix2D): Matrix2D {
         const result = Matrix2D.empty
         for (let i = 0; i < 3; i++) {
             for (let j = 0; j < 3; j++) {
@@ -90,7 +90,7 @@ export class Matrix2D {
      * representing the matrix elements.
      * @returns a new instance of the Matrix2D class, which is created using the result array.
      */
-    public static subtract(matrix1: Matrix2D, matrix2: Matrix2D): Matrix2D {
+    static subtract(matrix1: Matrix2D, matrix2: Matrix2D): Matrix2D {
         const result = Matrix2D.empty
         for (let i = 0; i < 3; i++) {
             for (let j = 0; j < 3; j++) {
@@ -106,7 +106,7 @@ export class Matrix2D {
      * @param {Matrix2D} matrix2 - The parameter `matrix2` is a 2D matrix of size 3x3.
      * @returns a new instance of the Matrix2D class, created using the result array.
      */
-    public static multiply(matrix1: Matrix2D, matrix2: Matrix2D): Matrix2D {
+    static multiply(matrix1: Matrix2D, matrix2: Matrix2D): Matrix2D {
         const result = Matrix2D.empty
         for (let i = 0; i < 3; i++) {
             for (let j = 0; j < 3; j++) {
@@ -126,7 +126,7 @@ export class Matrix2D {
      * @param {number} value - The `value` parameter is a number that you want to multiply each element of the `matrix` by.
      * @returns a new instance of the Matrix2D class, which is created using the result array.
      */
-    public static multiplyByValue(matrix: Matrix2D, value: number): Matrix2D {
+    static multiplyByValue(matrix: Matrix2D, value: number): Matrix2D {
         const result = Matrix2D.empty
         for (let i = 0; i < 3; i++) {
             for (let j = 0; j < 3; j++) {
@@ -142,7 +142,7 @@ export class Matrix2D {
      * @param {Vector2D} vector - The "vector" parameter is a 2D vector, represented by an object of type Vector2D.
      * @returns a Vector2D.
      */
-    public static multiplyByVector(matrix: Matrix2D, vector: Vector2D): Vector2D {
+    static multiplyByVector(matrix: Matrix2D, vector: Vector2D): Vector2D {
         return Matrix2D.multiply(matrix, new Matrix2D(vector)).toVector
     }
 
@@ -154,7 +154,7 @@ export class Matrix2D {
      * calculate the centerY value, which is the vertical center of the view.
      * @returns a Matrix2D object.
      */
-    public static view(width: number, height: number): Matrix2D {
+    static view(width: number, height: number): Matrix2D {
         const scaleStep = 1 // Scale every vector * scaleStep
         const centerX = width / 2
         const centerY = height / 2
@@ -172,7 +172,7 @@ export class Matrix2D {
      * should be scaled.
      * @returns the result of multiplying a new instance of Matrix2D by the given factor.
      */
-    public static scale(factor: number) {
+    static scale(factor: number) {
         return Matrix2D.multiplyByValue(new Matrix2D(), factor)
     }
 
@@ -181,7 +181,7 @@ export class Matrix2D {
      * @param {number} radians - The "radians" parameter is the angle in radians by which you want to rotate an object.
      * @returns The code is returning a new instance of a Matrix2D object.
      */
-    public static rotate(radians: number) {
+    static rotate(radians: number) {
         const cos = Math.cos(radians)
         const sin = Math.sin(radians)
 
@@ -197,7 +197,7 @@ export class Matrix2D {
      * and y, and an optional w component.
      * @returns The method is returning a new instance of the Matrix2D class.
      */
-    public static translate(vector: Vector2D): Matrix2D {
+    static translate(vector: Vector2D): Matrix2D {
         return new Matrix2D([
             [1, 0, vector.x],
             [0, 1, vector.y],
diff --git a/src/data-structures/matrix/vector2d.ts b/src/data-structures/matrix/vector2d.ts
index 6163194..4d6bdd8 100644
--- a/src/data-structures/matrix/vector2d.ts
+++ b/src/data-structures/matrix/vector2d.ts
@@ -17,7 +17,7 @@ export class Vector2D {
      * The function checks if the x and y values of a point are both zero.
      * @returns A boolean value indicating whether both the x and y properties of the object are equal to 0.
      */
-    public get isZero(): boolean {
+    get isZero(): boolean {
         return this.x === 0 && this.y === 0
     }
 
@@ -25,7 +25,7 @@ export class Vector2D {
      * The above function calculates the length of a vector using the Pythagorean theorem.
      * @returns The length of a vector, calculated using the Pythagorean theorem.
      */
-    public get length(): number {
+    get length(): number {
         return Math.sqrt((this.x * this.x) + (this.y * this.y))
     }
 
@@ -33,7 +33,7 @@ export class Vector2D {
      * The function calculates the square of the length of a vector.
      * @returns The method is returning the sum of the squares of the x and y values.
      */
-    public get lengthSq(): number {
+    get lengthSq(): number {
         return (this.x * this.x) + (this.y * this.y)
     }
 
@@ -42,7 +42,7 @@ export class Vector2D {
      * @returns The method is returning a new instance of the Vector2D class with the x and y values rounded to the nearest
      * whole number.
      */
-    public get rounded(): Vector2D {
+    get rounded(): Vector2D {
         return new Vector2D(Math.round(this.x), Math.round(this.y))
     }
 
@@ -56,7 +56,7 @@ export class Vector2D {
      * @returns The method is returning a new instance of the Vector2D class with the x and y components of the two input
      * vectors added together.
      */
-    public static add(vector1: Vector2D, vector2: Vector2D): Vector2D {
+    static add(vector1: Vector2D, vector2: Vector2D): Vector2D {
         return new Vector2D(vector1.x + vector2.x, vector1.y + vector2.y)
     }
 
@@ -71,7 +71,7 @@ export class Vector2D {
      * @returns The method is returning a new Vector2D object with the x and y components subtracted from vector1 and
      * vector2.
      */
-    public static subtract(vector1: Vector2D, vector2: Vector2D): Vector2D {
+    static subtract(vector1: Vector2D, vector2: Vector2D): Vector2D {
         return new Vector2D(vector1.x - vector2.x, vector1.y - vector2.y)
     }
 
@@ -84,7 +84,7 @@ export class Vector2D {
      * of the "vector" parameter.
      * @returns A new Vector2D object with the x and y values subtracted by the given value.
      */
-    public static subtractValue(vector: Vector2D, value: number): Vector2D {
+    static subtractValue(vector: Vector2D, value: number): Vector2D {
         return new Vector2D(vector.x - value, vector.y - value)
     }
 
@@ -96,7 +96,7 @@ export class Vector2D {
      * of the vector will be multiplied.
      * @returns A new Vector2D object with the x and y values multiplied by the given value.
      */
-    public static multiply(vector: Vector2D, value: number): Vector2D {
+    static multiply(vector: Vector2D, value: number): Vector2D {
         return new Vector2D(vector.x * value, vector.y * value)
     }
 
@@ -108,7 +108,7 @@ export class Vector2D {
      * vector.
      * @returns A new instance of the Vector2D class with the x and y values divided by the given value.
      */
-    public static divide(vector: Vector2D, value: number): Vector2D {
+    static divide(vector: Vector2D, value: number): Vector2D {
         return new Vector2D(vector.x / value, vector.y / value)
     }
 
@@ -119,7 +119,7 @@ export class Vector2D {
      * @param {Vector2D} vector2 - The parameter "vector2" is of type Vector2D.
      * @returns a boolean value, which indicates whether the two input vectors are equal or not.
      */
-    public static equals(vector1: Vector2D, vector2: Vector2D): boolean {
+    static equals(vector1: Vector2D, vector2: Vector2D): boolean {
         return vector1.x === vector2.x && vector1.y === vector2.y
     }
 
@@ -133,7 +133,7 @@ export class Vector2D {
      * roundingFactor, the vectors are considered equal.
      * @returns a boolean value.
      */
-    public static equalsRounded(vector1: Vector2D, vector2: Vector2D, roundingFactor = 12): boolean {
+    static equalsRounded(vector1: Vector2D, vector2: Vector2D, roundingFactor = 12): boolean {
         const vector = Vector2D.abs(Vector2D.subtract(vector1, vector2))
         if (vector.x < roundingFactor && vector.y < roundingFactor) {
             return true
@@ -148,7 +148,7 @@ export class Vector2D {
      * @returns the normalized vector if its length is greater than a very small value (epsilon), otherwise it returns the
      * original vector.
      */
-    public static normalize(vector: Vector2D): Vector2D {
+    static normalize(vector: Vector2D): Vector2D {
         const length = vector.length
         if (length > 2.220446049250313e-16) { // Epsilon
             return Vector2D.divide(vector, length)
@@ -165,7 +165,7 @@ export class Vector2D {
      * @returns either the original vector or a truncated version of the vector, depending on whether the length of the
      * vector is greater than the maximum value specified.
      */
-    public static truncate(vector: Vector2D, max: number): Vector2D {
+    static truncate(vector: Vector2D, max: number): Vector2D {
         if (vector.length > max) {
             return Vector2D.multiply(Vector2D.normalize(vector), max)
         }
@@ -178,7 +178,7 @@ export class Vector2D {
      * @param {Vector2D} vector - The parameter "vector" is of type Vector2D.
      * @returns A new Vector2D object is being returned.
      */
-    public static perp(vector: Vector2D): Vector2D {
+    static perp(vector: Vector2D): Vector2D {
         return new Vector2D(-vector.y, vector.x)
     }
 
@@ -188,7 +188,7 @@ export class Vector2D {
      * has two properties: "x" and "y", which represent the x and y components of the vector, respectively.
      * @returns A new Vector2D object with the negated x and y values of the input vector. Returns the vector that is the reverse of this vector
      */
-    public static reverse(vector: Vector2D): Vector2D {
+    static reverse(vector: Vector2D): Vector2D {
         return new Vector2D(-vector.x, -vector.y)
     }
 
@@ -200,7 +200,7 @@ export class Vector2D {
      * @returns The method is returning a new Vector2D object with the absolute values of the x and y components of the
      * input vector.
      */
-    public static abs(vector: Vector2D): Vector2D {
+    static abs(vector: Vector2D): Vector2D {
         return new Vector2D(Math.abs(vector.x), Math.abs(vector.y))
     }
 
@@ -211,7 +211,7 @@ export class Vector2D {
      * with an x and y component.
      * @returns The dot product of the two input vectors.
      */
-    public static dot(vector1: Vector2D, vector2: Vector2D): number {
+    static dot(vector1: Vector2D, vector2: Vector2D): number {
         return (vector1.x * vector2.x) + (vector1.y * vector2.y)
     }
 
@@ -219,7 +219,7 @@ export class Vector2D {
     //  * Transform vectors based on the current tranformation matrices: translation, rotation and scale
     //  * @param vectors The vectors to transform
     //  */
-    // public static transform(vector: Vector2D, transformation: Matrix2D): Vector2D {
+    // static transform(vector: Vector2D, transformation: Matrix2D): Vector2D {
     //     return Matrix2D.multiplyByVector(transformation, vector)
     // }
 
@@ -227,7 +227,7 @@ export class Vector2D {
     //  * Transform vectors based on the current tranformation matrices: translation, rotation and scale
     //  * @param vectors The vectors to transform
     //  */
-    // public static transformList(vectors: Vector2D[], transformation: Matrix2D): Vector2D[] {
+    // static transformList(vectors: Vector2D[], transformation: Matrix2D): Vector2D[] {
     //     return vectors.map(vector => Matrix2D.multiplyByVector(transformation, vector))
     // }
 
@@ -241,7 +241,7 @@ export class Vector2D {
      * the vector in a 2D space.
      * @returns The distance between vector1 and vector2.
      */
-    public static distance(vector1: Vector2D, vector2: Vector2D): number {
+    static distance(vector1: Vector2D, vector2: Vector2D): number {
         const ySeparation = vector2.y - vector1.y
         const xSeparation = vector2.x - vector1.x
         return Math.sqrt((ySeparation * ySeparation) + (xSeparation * xSeparation))
@@ -255,7 +255,7 @@ export class Vector2D {
      * properties `x` and `y` which represent the coordinates of the vector.
      * @returns the square of the distance between the two input vectors.
      */
-    public static distanceSq(vector1: Vector2D, vector2: Vector2D): number {
+    static distanceSq(vector1: Vector2D, vector2: Vector2D): number {
         const ySeparation = vector2.y - vector1.y
         const xSeparation = vector2.x - vector1.x
         return (ySeparation * ySeparation) + (xSeparation * xSeparation)
@@ -270,7 +270,7 @@ export class Vector2D {
      * vector2. Both vector1 and vector2 are of type Vector2D.
      * @returns either -1 or 1. Returns positive if v2 is clockwise of this vector, negative if counterclockwise
      */
-    public static sign(vector1: Vector2D, vector2: Vector2D): number {
+    static sign(vector1: Vector2D, vector2: Vector2D): number {
         if (vector1.y * vector2.x > vector1.x * vector2.y) {
             return -1
         }
@@ -285,7 +285,7 @@ export class Vector2D {
      * respectively.
      * @returns the angle between the given vector and the vector (0, -1) in radians.Returns the angle between origin and the given vector in radians
      */
-    public static angle(vector: Vector2D): number {
+    static angle(vector: Vector2D): number {
         const origin = new Vector2D(0, -1)
         const radian = Math.acos(Vector2D.dot(vector, origin) / (vector.length * origin.length))
         return Vector2D.sign(vector, origin) === 1 ? ((Math.PI * 2) - radian) : radian
@@ -298,7 +298,7 @@ export class Vector2D {
      * random vector.
      * @returns a new instance of the Vector2D class with random x and y values.
      */
-    public static random(maxX: number, maxY: number): Vector2D {
+    static random(maxX: number, maxY: number): Vector2D {
         const randX = Math.floor(Math.random() * maxX - (maxX / 2))
         const randY = Math.floor(Math.random() * maxY - (maxY / 2))
         return new Vector2D(randX, randY)
@@ -307,7 +307,7 @@ export class Vector2D {
     /**
      * The function sets the values of x and y to zero.
      */
-    public zero(): void {
+    zero(): void {
         this.x = 0
         this.y = 0
     }
diff --git a/tests/unit/data-structures/constants/index.ts b/tests/unit/data-structures/constants/index.ts
new file mode 100644
index 0000000..27b2090
--- /dev/null
+++ b/tests/unit/data-structures/constants/index.ts
@@ -0,0 +1 @@
+export * from './magnitude';
\ No newline at end of file
diff --git a/tests/unit/data-structures/constants/magnitude.ts b/tests/unit/data-structures/constants/magnitude.ts
new file mode 100644
index 0000000..eaed3fe
--- /dev/null
+++ b/tests/unit/data-structures/constants/magnitude.ts
@@ -0,0 +1,11 @@
+const orderReducedBy = 2; // reduction of magnitude's order compared to the baseline magnitude
+
+export const magnitude = {
+    CONSTANT: Math.floor(Number.MAX_SAFE_INTEGER / Math.pow(10, orderReducedBy)),
+    LOG_N: Math.pow(10, 9 - orderReducedBy),
+    LINEAR: Math.pow(10, 6 - orderReducedBy),
+    N_LOG_N: Math.pow(10, 5 - orderReducedBy),
+    SQUARED: Math.pow(10, 4 - orderReducedBy),
+    CUBED: Math.pow(10, 3 - orderReducedBy),
+    FACTORIAL: 20 - orderReducedBy
+}
\ No newline at end of file
diff --git a/tests/unit/data-structures/linked-list/doubly-linked-list.test.ts b/tests/unit/data-structures/linked-list/doubly-linked-list.test.ts
index 8a0b052..bdc68de 100644
--- a/tests/unit/data-structures/linked-list/doubly-linked-list.test.ts
+++ b/tests/unit/data-structures/linked-list/doubly-linked-list.test.ts
@@ -1,4 +1,5 @@
 import {DoublyLinkedList} from '../../../../src';
+import {magnitude} from '../constants';
 
 describe('DoublyLinkedList Operation Test', () => {
     let list: DoublyLinkedList<number>;
@@ -39,19 +40,19 @@ describe('DoublyLinkedList Operation Test', () => {
         list.push(3);
 
         // Inserting at the beginning
-        list.insert(0, 0);
+        list.insertAt(0, 0);
         expect(list.length).toBe(4);
         expect(list.getAt(0)).toBe(0);
         expect(list.getAt(1)).toBe(1);
 
         // Inserting in the middle
-        list.insert(2, 1.5);
+        list.insertAt(2, 1.5);
         expect(list.length).toBe(5);
         expect(list.getAt(2)).toBe(1.5);
         expect(list.getAt(3)).toBe(2);
 
         // Inserting at the end
-        list.insert(5, 4);
+        list.insertAt(5, 4);
         expect(list.length).toBe(6);
         expect(list.getAt(5)).toBe(4);
         expect(list.tail!.val).toBe(4);
@@ -344,24 +345,21 @@ describe('DoublyLinkedList Operation Test', () => {
 describe('DoublyLinkedList Performance Test', () => {
     describe('should the push and pop methods adhere to a time complexity of O(n) and executed correctly under large scale data', () => {
         const list = new DoublyLinkedList<number>();
-        const iterations = 10000;
 
         const startPushTime = performance.now();
-        for (let i = 0; i < iterations; i++) {
+        for (let i = 0; i < magnitude.LINEAR; i++) {
             list.unshift(i);
         }
-        expect(performance.now() - startPushTime).toBeLessThan(iterations * 1000);
+        expect(performance.now() - startPushTime).toBeLessThan(magnitude.LINEAR * 1000);
 
         const startPopTime = performance.now();
 
         expect(list.length).toBeGreaterThan(0);
-        for (let i = 0; i < iterations; i++) {
+        for (let i = 0; i < magnitude.LINEAR; i++) {
             list.shift();
         }
         expect(list.pop()).toBeNull();
         expect(list.length).toBe(0);
-        expect(performance.now() - startPopTime).toBeLessThan(iterations * 1000);
-
+        expect(performance.now() - startPopTime).toBeLessThan(magnitude.LINEAR * 1000);
     });
-
 });
\ No newline at end of file
diff --git a/tests/unit/data-structures/linked-list/index.ts b/tests/unit/data-structures/linked-list/index.ts
index 832f869..3b50503 100644
--- a/tests/unit/data-structures/linked-list/index.ts
+++ b/tests/unit/data-structures/linked-list/index.ts
@@ -1,2 +1,4 @@
 export * from './singly-linked-list.test';
 export * from './doubly-linked-list.test';
+export * from './linked-list.test';
+export * from './skip-linked-list.test';
diff --git a/tests/unit/data-structures/linked-list/linked-list.test.ts b/tests/unit/data-structures/linked-list/linked-list.test.ts
new file mode 100644
index 0000000..a2844c7
--- /dev/null
+++ b/tests/unit/data-structures/linked-list/linked-list.test.ts
@@ -0,0 +1,37 @@
+import {DoublyLinkedList, DoublyLinkedListNode, SinglyLinkedList, SinglyLinkedListNode} from '../../../../src';
+import {magnitude} from '../constants';
+
+describe('LinkedList Performance Test', () => {
+    it('should DoublyLinkedList insertBefore faster than SinglyLinkedList', () => {
+        const doublyList = new DoublyLinkedList<number>();
+
+        const startPushTime = performance.now();
+        let midNode: DoublyLinkedListNode | null = null;
+        const midIndex = Math.floor((magnitude.SQUARED) / 2);
+        for (let i = 0; i < magnitude.SQUARED; i++) {
+            doublyList.push(i);
+            if (i === midIndex) {
+                midNode = doublyList.findNode(i);
+            } else if (i > midIndex && midNode) {
+                doublyList.insertBefore(midNode, i);
+            }
+        }
+        const doublyListPushCost = performance.now() - startPushTime;
+
+        const singlyList = new SinglyLinkedList<number>();
+        let midSinglyNode: SinglyLinkedListNode | null = null;
+
+        const startSinglyPushTime = performance.now();
+        for (let i = 0; i < magnitude.SQUARED; i++) {
+            singlyList.push(i);
+            if (i === midIndex) {
+                midSinglyNode = singlyList.findNode(i);
+            } else if (i > midIndex && midSinglyNode) {
+                singlyList.insertBefore(midSinglyNode.val, i);
+            }
+        }
+
+        const singlyListPushCost = performance.now() - startSinglyPushTime;
+        expect(doublyListPushCost).toBeLessThan(Math.sqrt(singlyListPushCost) + 1000);
+    });
+});
\ No newline at end of file
diff --git a/tests/unit/data-structures/linked-list/singly-linked-list.test.ts b/tests/unit/data-structures/linked-list/singly-linked-list.test.ts
index a46917d..83fa389 100644
--- a/tests/unit/data-structures/linked-list/singly-linked-list.test.ts
+++ b/tests/unit/data-structures/linked-list/singly-linked-list.test.ts
@@ -1,4 +1,5 @@
 import {SinglyLinkedList} from '../../../../src';
+import {magnitude} from '../constants';
 
 describe('SinglyLinkedList Operation Test', () => {
     let list: SinglyLinkedList<number>;
@@ -296,9 +297,9 @@ describe('SinglyLinkedList Operation Test', () => {
 
     describe('insert and toArray', () => {
         it('should insert elements and return array correctly', () => {
-            list.insert(0, 1);
-            list.insert(1, 3);
-            list.insert(1, 2);
+            list.insertAt(0, 1);
+            list.insertAt(1, 3);
+            list.insertAt(1, 2);
             expect(list.toArray()).toEqual([1, 2, 3]);
         });
     });
@@ -381,21 +382,20 @@ describe('SinglyLinkedList Operation Test', () => {
 describe('SinglyLinkedList Performance Test', () => {
     describe('should the push and pop methods adhere to a time complexity of O(n) and executed correctly under large scale data', () => {
         const list = new SinglyLinkedList<number>();
-        const iterations = 10000; // Adjust the number of iterations as needed
 
         const startPushTime = performance.now();
-        for (let i = 0; i < iterations; i++) {
+        for (let i = 0; i < magnitude.LINEAR; i++) {
             list.push(i);
         }
-        expect(performance.now() - startPushTime).toBeLessThan(iterations * 1000);
+        expect(performance.now() - startPushTime).toBeLessThan(magnitude.LINEAR * 1000);
 
         const startPopTime = performance.now();
 
-        for (let i = 0; i < iterations; i++) {
+        for (let i = 0; i < magnitude.LINEAR; i++) {
             list.pop();
         }
 
-        expect(performance.now() - startPopTime).toBeLessThan(iterations * 1000);
+        expect(performance.now() - startPopTime).toBeLessThan(magnitude.LINEAR * 1000);
 
     });
 });
\ No newline at end of file
diff --git a/tests/unit/data-structures/linked-list/skip-linked-list.ts b/tests/unit/data-structures/linked-list/skip-linked-list.test.ts
similarity index 60%
rename from tests/unit/data-structures/linked-list/skip-linked-list.ts
rename to tests/unit/data-structures/linked-list/skip-linked-list.test.ts
index 6ba4fd6..42f3953 100644
--- a/tests/unit/data-structures/linked-list/skip-linked-list.ts
+++ b/tests/unit/data-structures/linked-list/skip-linked-list.test.ts
@@ -1,11 +1,13 @@
+import {SkipLinkedList} from '../../../../src'
+
 describe('SkipLinkedList Operation Test', () => {
     it('should xxx', function () {
-
+        const xxx = new SkipLinkedList();
     });
 });
 
 describe('SkipLinkedList Performance Test', () => {
     it('should xxx', function () {
-
+        const xxx = new SkipLinkedList();
     });
 });
\ No newline at end of file
diff --git a/tests/unit/data-structures/priority-queue/max-priority-queue.test.ts b/tests/unit/data-structures/priority-queue/max-priority-queue.test.ts
index cd056be..02f3428 100644
--- a/tests/unit/data-structures/priority-queue/max-priority-queue.test.ts
+++ b/tests/unit/data-structures/priority-queue/max-priority-queue.test.ts
@@ -1,4 +1,5 @@
 import {MaxPriorityQueue} from '../../../../src';
+import {magnitude} from '../constants';
 
 describe('MaxPriorityQueue Operation Test', () => {
 
@@ -79,9 +80,8 @@ describe('MaxPriorityQueue Operation Test', () => {
 describe('MaxPriorityQueue Performance Test', () => {
 
     it('should the poll method adheres to a time complexity of O(log n) and executed correctly under large scale distinct data', () => {
-        const magnitude = 10000;
-        const nodes = Array.from(new Set<number>(Array.from(new Array(magnitude), () => Math.floor(Math.random() * magnitude * 100))));
-        expect(nodes.length).toBeGreaterThan(magnitude / 2);
+        const nodes = Array.from(new Set<number>(Array.from(new Array(magnitude.LINEAR), () => Math.floor(Math.random() * magnitude.LINEAR * 100))));
+        expect(nodes.length).toBeGreaterThan(magnitude.LINEAR / 2);
         const maxPQ = new MaxPriorityQueue<number>({nodes});
 
         let prev = Number.MAX_SAFE_INTEGER;
@@ -93,7 +93,7 @@ describe('MaxPriorityQueue Performance Test', () => {
                 prev = polled;
             }
         }
-        expect(performance.now() - startTime).toBeLessThan(Math.log2(magnitude) * 1000);
+        expect(performance.now() - startTime).toBeLessThan(Math.log2(magnitude.LINEAR) * 1000);
     });
 
     it('should sorted.length to be the same as original data', () => {