diff --git a/src/data-structures/binary-tree/avl-tree.ts b/src/data-structures/binary-tree/avl-tree.ts
index 282fd21..d095a27 100644
--- a/src/data-structures/binary-tree/avl-tree.ts
+++ b/src/data-structures/binary-tree/avl-tree.ts
@@ -7,22 +7,17 @@
  */
 import {BST, BSTNode} from './bst';
 import type {AVLTreeDeleted, BinaryTreeNodeId} from '../types';
+import {IBinaryTreeNode} from '../interfaces';
 
-export class AVLTreeNode<T> extends BSTNode<T> {
-    /**
-     * The function overrides the clone method of the AVLTreeNode class to create a new AVLTreeNode object with the same
-     * id, value, and count.
-     * @returns The method is returning a new instance of the AVLTreeNode class with the same id, val, and count values as
-     * the current instance.
-     */
-    override clone(): AVLTreeNode<T> {
-        return new AVLTreeNode<T>(this.id, this.val, this.count);
+export class AVLTreeNode<T> extends BSTNode<T> implements IBinaryTreeNode<T> {
+    override _createNode(id: BinaryTreeNodeId, val: T | null, count?: number): AVLTreeNode<T> | null {
+        return val !== null ? new AVLTreeNode<T>(id, val, count) : null;
     }
 }
 
 export class AVLTree<T> extends BST<T> {
 
-    override createNode(id: BinaryTreeNodeId, val: T, count?: number): AVLTreeNode<T> {
+    override _createNode(id: BinaryTreeNodeId, val: T, count?: number): AVLTreeNode<T> {
         return new AVLTreeNode<T>(id, val, count);
     }
 
diff --git a/src/data-structures/binary-tree/binary-tree.ts b/src/data-structures/binary-tree/binary-tree.ts
index c6e4682..fb2faae 100644
--- a/src/data-structures/binary-tree/binary-tree.ts
+++ b/src/data-structures/binary-tree/binary-tree.ts
@@ -16,6 +16,7 @@ import type {
     ResultByProperty,
     ResultsByProperty
 } from '../types';
+import {IBinaryTree, IBinaryTreeNode} from '../interfaces';
 
 /* This enumeration defines the position of a node within a family tree composed of three associated nodes, where 'root' represents the root node of the family tree, 'left' represents the left child node, and 'right' represents the right child node. */
 export enum FamilyPosition {root, left, right}
@@ -28,7 +29,7 @@ export enum FamilyPosition {root, left, right}
  */
 export enum LoopType { iterative = 1, recursive = 2}
 
-export class BinaryTreeNode<T> {
+export class BinaryTreeNode<T> implements IBinaryTreeNode<T> {
 
     constructor(id: BinaryTreeNodeId, val: T, count?: number) {
         this._id = id;
@@ -47,6 +48,7 @@ export class BinaryTreeNode<T> {
     }
 
     private _val: T;
+
     get val(): T {
         return this._val;
     }
@@ -123,31 +125,37 @@ export class BinaryTreeNode<T> {
         this._height = v;
     }
 
+    _createNode(id: BinaryTreeNodeId, val: T | null, count?: number): BinaryTreeNode<T> | null {
+        return val !== null ? new BinaryTreeNode<T>(id, val, count) : null;
+    }
+
     swapLocation(swapNode: BinaryTreeNode<T>): BinaryTreeNode<T> {
         const {val, count, height} = swapNode;
-        const tempNode = new BinaryTreeNode<T>(swapNode.id, val);
-        tempNode.val = val;
-        tempNode.count = count;
-        tempNode.height = height;
+        const tempNode = this._createNode(swapNode.id, val);
+        if (tempNode instanceof BinaryTreeNode) {
+            tempNode.val = val;
+            tempNode.count = count;
+            tempNode.height = height;
 
-        swapNode.id = this.id;
-        swapNode.val = this.val;
-        swapNode.count = this.count;
-        swapNode.height = this.height;
+            swapNode.id = this.id;
+            swapNode.val = this.val;
+            swapNode.count = this.count;
+            swapNode.height = this.height;
 
-        this.id = tempNode.id;
-        this.val = tempNode.val;
-        this.count = tempNode.count;
-        this.height = tempNode.height;
+            this.id = tempNode.id;
+            this.val = tempNode.val;
+            this.count = tempNode.count;
+            this.height = tempNode.height;
+        }
         return swapNode;
     }
 
-    clone(): BinaryTreeNode<T> {
-        return new BinaryTreeNode<T>(this.id, this.val, this.count);
+    clone(): BinaryTreeNode<T> | null {
+        return this._createNode(this.id, this.val, this.count);
     }
 }
 
-export class BinaryTree<T> {
+export class BinaryTree<T> implements IBinaryTree<T> {
 
     /**
      * The constructor function accepts an optional options object and sets the values of loopType, autoIncrementId, and
@@ -243,19 +251,18 @@ export class BinaryTree<T> {
     }
 
     /**
-     * The function creates a new binary tree node with the given id, value, and count, or returns null if the value is
-     * null.
+     * The function creates a new binary tree node with the given id, value, and count if the value is not null, otherwise
+     * it returns null.
      * @param {BinaryTreeNodeId} id - The `id` parameter is the identifier for the binary tree node. It is of type
-     * `BinaryTreeNodeId`, which could be a string or a number, depending on how you want to identify your nodes.
-     * @param {T | null} val - The `val` parameter represents the value to be stored in the binary tree node. It can be of
-     * any type `T` or `null`.
-     * @param {number} [count] - The count parameter is an optional parameter that represents the number of occurrences of
-     * the value in the binary tree node. It is of type number.
-     * @returns The function `createNode` returns a `BinaryTreeNode<T>` object if the `val` parameter is not null.
-     * Otherwise, it returns null.
+     * `BinaryTreeNodeId`.
+     * @param {T | null} val - The `val` parameter represents the value of the node. It can be of type `T` (generic type)
+     * or `null`.
+     * @param {number} [count] - The `count` parameter is an optional parameter of type `number`. It represents the number
+     * of occurrences of the value in the binary tree node. If not provided, the default value is `undefined`.
+     * @returns a BinaryTreeNode object if the value is not null, otherwise it returns null.
      */
-    createNode(id: BinaryTreeNodeId, val: T | null, count?: number): BinaryTreeNode<T> | null {
-        return val !== null ? new BinaryTreeNode(id, val, count) : null;
+    _createNode(id: BinaryTreeNodeId, val: T | null, count?: number): BinaryTreeNode<T> | null {
+        return val !== null ? new BinaryTreeNode<T>(id, val, count) : null;
     }
 
     /**
@@ -305,7 +312,7 @@ export class BinaryTree<T> {
         };
 
         let inserted: BinaryTreeNode<T> | null | undefined;
-        const needInsert = val !== null ? new BinaryTreeNode<T>(id, val, count) : null;
+        const needInsert = val !== null ? this._createNode(id, val, count) : null;
         const existNode = val !== null ? this.get(id, 'id') : null;
         if (this.root) {
             if (existNode) {
@@ -319,7 +326,7 @@ export class BinaryTree<T> {
                 inserted = _bfs(this.root, needInsert);
             }
         } else {
-            this._setRoot(val !== null ? new BinaryTreeNode<T>(id, val, count) : null);
+            this._setRoot(val !== null ? this._createNode(id, val, count) : null);
             if (needInsert !== null) {
                 this._setSize(1);
                 this._setCount(count);
diff --git a/src/data-structures/binary-tree/bst.ts b/src/data-structures/binary-tree/bst.ts
index 6641b44..e06c078 100644
--- a/src/data-structures/binary-tree/bst.ts
+++ b/src/data-structures/binary-tree/bst.ts
@@ -7,16 +7,17 @@
  */
 import type {BinaryTreeNodeId, BinaryTreeNodePropertyName, BSTComparator, BSTDeletedResult} from '../types';
 import {BinaryTree, BinaryTreeNode, FamilyPosition, LoopType,} from './binary-tree';
+import {IBinaryTree, IBinaryTreeNode} from '../interfaces';
 
 export enum CP {lt = -1, eq = 0, gt = 1}
 
-export class BSTNode<T> extends BinaryTreeNode<T> {
-    override clone(): BSTNode<T> {
-        return new BSTNode<T>(this.id, this.val, this.count);
+export class BSTNode<T> extends BinaryTreeNode<T> implements IBinaryTreeNode<T> {
+    override _createNode(id: BinaryTreeNodeId, val: T | null, count?: number): BSTNode<T> | null {
+        return val !== null ? new BSTNode<T>(id, val, count) : null;
     }
 }
 
-export class BST<T> extends BinaryTree<T> {
+export class BST<T> extends BinaryTree<T> implements IBinaryTree<T> {
     /**
      * The constructor function accepts an optional options object and sets the comparator property if provided.
      * @param [options] - An optional object that can contain the following properties:
@@ -34,7 +35,7 @@ export class BST<T> extends BinaryTree<T> {
         }
     }
 
-    override createNode(id: BinaryTreeNodeId, val: T | null, count?: number): BSTNode<T> | null {
+    override _createNode(id: BinaryTreeNodeId, val: T | null, count?: number): BSTNode<T> | null {
         return val !== null ? new BSTNode<T>(id, val, count) : null;
     }
 
@@ -52,7 +53,7 @@ export class BST<T> extends BinaryTree<T> {
      */
     override add(id: BinaryTreeNodeId, val: T | null, count: number = 1): BSTNode<T> | null {
         let inserted: BSTNode<T> | null = null;
-        const newNode = this.createNode(id, val, count);
+        const newNode = this._createNode(id, val, count);
         if (this.root === null) {
             this._setRoot(newNode);
             this._setSize(this.size + 1);
diff --git a/src/data-structures/binary-tree/rb-tree.ts b/src/data-structures/binary-tree/rb-tree.ts
index 097b542..f9e0fe7 100644
--- a/src/data-structures/binary-tree/rb-tree.ts
+++ b/src/data-structures/binary-tree/rb-tree.ts
@@ -1,3 +1,110 @@
-export class RBTree {
+import {BinaryTree, BinaryTreeNode, LoopType} from './binary-tree';
+import {IBinaryTree, IBinaryTreeNode} from '../interfaces';
+
+enum RBColor { Red, Black }
+
+class RBNode<T> extends BinaryTreeNode<T> implements IBinaryTreeNode<T> {
+    // override createNode(id: BinaryTreeNodeId, val: T | null, count?: number): RBNode<T> | null {
+    //     return val !== null ? new RBNode<T>(id, val, count) : null;
+    // }
+
+    constructor(id: number, val: T, count?: number) {
+        super(id, val, count);
+    }
+
+    private _color: RBColor = RBColor.Red;
+
+    get color(): RBColor {
+        return this._color;
+    }
+
+    set color(value: RBColor) {
+        this._color = value;
+    }
+
+    // private override _parent: RBNode<T> | null;
+    // override set parent(v: RBNode<T> | null) {
+    //     this._parent = v;
+    // }
+    // override get parent(): RBNode<T> | null {
+    //     return this._parent;
+    // }
+    // private override _left?: RBNode<T> | null;
+    //
+    // override get left(): RBNode<T> | null | undefined {
+    //     return this._left;
+    // }
+    //
+    // override set left(v: RBNode<T> | null | undefined) {
+    //     if (v) {
+    //         v.parent = this;
+    //         v.familyPosition = FamilyPosition.left;
+    //     }
+    //     this._left = v;
+    // }
+    //
+    // private override _right?: RBNode<T> | null;
+    //
+    // override get right(): RBNode<T> | null | undefined {
+    //     return this._right;
+    // }
+    //
+    // override set right(v: RBNode<T> | null | undefined) {
+    //     if (v) {
+    //         v.parent = this;
+    //         v.familyPosition = FamilyPosition.right;
+    //     }
+    //     this._right = v;
+    // }
+}
+
+class RBTree<T> extends BinaryTree<T> implements IBinaryTree<T> {
+    constructor(options?: {
+        loopType?: LoopType,
+        autoIncrementId?: boolean,
+        isDuplicatedVal?: boolean
+    }) {
+        super(options);
+    }
+
+    // override _createNode(id: BinaryTreeNodeId, val: T | null, count?: number): RBNode<T> | null {
+    //     return val !== null ? new RBNode<T>(id, val, count) : null;
+    // }
+
+    // private override _root: BinaryTreeNode<T> | null = null;
+    //
+    // override get root(): BinaryTreeNode<T> | null {
+    //     return this._root;
+    // }
+
+    insert(id: number, val: T | null) {
+
+    }
+
+    private leftRotate(node: RBNode<T>) {
+
+    }
+
+    private rightRotate(node: RBNode<T>) {
+
+    }
+
+    private insertFixup(node: RBNode<T>) {
+
+    }
+
+    private deleteFixup(node: RBNode<T>) {
+
+    }
+
+    private transplant(u: RBNode<T>, v: RBNode<T>) {
+
+    }
+
+    // override remove(id: BinaryTreeNodeId, ignoreCount?: boolean): BinaryTreeDeleted<T>[] {
+    //
+    //     return [{deleted: new RBNode<T>(0, 0), needBalanced: null}];
+    // }
+
 
 }
diff --git a/src/data-structures/binary-tree/tree-multiset.ts b/src/data-structures/binary-tree/tree-multiset.ts
index 8dc7926..46d9405 100644
--- a/src/data-structures/binary-tree/tree-multiset.ts
+++ b/src/data-structures/binary-tree/tree-multiset.ts
@@ -7,8 +7,9 @@
  */
 import {BST, BSTNode} from './bst';
 import type {BinaryTreeNodeId, TreeMultiSetDeletedResult} from '../types';
+import {IBinaryTree} from '../interfaces';
 
-export class TreeMultiSet<T> extends BST<T> {
+export class TreeMultiSet<T> extends BST<T> implements IBinaryTree<T> {
     /**
      * The function creates a new BSTNode with the given id, value, and count.
      * @param {BinaryTreeNodeId} id - The id parameter is the unique identifier for the binary tree node. It is used to
@@ -18,7 +19,7 @@ export class TreeMultiSet<T> extends BST<T> {
      * occurrences of the value in the binary search tree node. If not provided, the count will default to 1.
      * @returns A new instance of the BSTNode class with the specified id, value, and count (if provided).
      */
-    override createNode(id: BinaryTreeNodeId, val: T, count?: number): BSTNode<T> {
+    override _createNode(id: BinaryTreeNodeId, val: T, count?: number): BSTNode<T> {
         return new BSTNode<T>(id, val, count);
     }
 
diff --git a/src/data-structures/graph/abstract-graph.ts b/src/data-structures/graph/abstract-graph.ts
index 2d2db55..1c96c97 100644
--- a/src/data-structures/graph/abstract-graph.ts
+++ b/src/data-structures/graph/abstract-graph.ts
@@ -7,7 +7,8 @@
  */
 import {arrayRemove, uuidV4} from '../../utils';
 import {PriorityQueue} from '../priority-queue';
-import type {DijkstraResult, IGraph, VertexId} from '../types';
+import type {DijkstraResult, VertexId} from '../types';
+import {IGraph} from '../interfaces';
 
 export class AbstractVertex {
     constructor(id: VertexId) {
@@ -389,7 +390,7 @@ export abstract class AbstractGraph<V extends AbstractVertex, E extends Abstract
      * @returns The function `dijkstraWithoutHeap` returns an object of type `DijkstraResult<V>`.
      */
     dijkstraWithoutHeap(src: V | VertexId, dest?: V | VertexId | null, getMinDist?: boolean, genPaths?: boolean): DijkstraResult<V> {
-        if (getMinDist === undefined) getMinDist = false ;
+        if (getMinDist === undefined) getMinDist = false;
         if (genPaths === undefined) genPaths = false;
 
         if (dest === undefined) dest = null;
diff --git a/src/data-structures/graph/directed-graph.ts b/src/data-structures/graph/directed-graph.ts
index 41e6b86..abd7fca 100644
--- a/src/data-structures/graph/directed-graph.ts
+++ b/src/data-structures/graph/directed-graph.ts
@@ -7,7 +7,8 @@
  */
 import {arrayRemove} from '../../utils';
 import {AbstractEdge, AbstractGraph, AbstractVertex} from './abstract-graph';
-import type {IDirectedGraph, TopologicalStatus, VertexId} from '../types';
+import type {TopologicalStatus, VertexId} from '../types';
+import {IDirectedGraph} from '../interfaces';
 
 export class DirectedVertex extends AbstractVertex {
     /**
diff --git a/src/data-structures/hash/coordinate-set.ts b/src/data-structures/hash/coordinate-set.ts
index 937ea7e..7d65fd1 100644
--- a/src/data-structures/hash/coordinate-set.ts
+++ b/src/data-structures/hash/coordinate-set.ts
@@ -5,7 +5,7 @@
  * @copyright Copyright (c) 2022 Tyler Zeng <zrwusa@gmail.com>
  * @license MIT License
  */
-export class CoordinateSet extends Set {
+export class CoordinateSet extends Set<any> {
     constructor(joint?: string) {
         super();
         if (joint !== undefined) this._joint = joint;
diff --git a/src/data-structures/index.ts b/src/data-structures/index.ts
index c431497..9dfa0b2 100644
--- a/src/data-structures/index.ts
+++ b/src/data-structures/index.ts
@@ -9,6 +9,7 @@ export * from './heap';
 export * from './priority-queue';
 export * from './matrix';
 export * from './trie';
+export * from './interfaces';
 export * from './types';
 
 
diff --git a/src/data-structures/interfaces/abstract-graph.ts b/src/data-structures/interfaces/abstract-graph.ts
new file mode 100644
index 0000000..50d08f8
--- /dev/null
+++ b/src/data-structures/interfaces/abstract-graph.ts
@@ -0,0 +1,40 @@
+import {VertexId} from '../types';
+
+export interface IGraph<V, E> {
+
+    hasVertex(vertexOrId: V | VertexId): boolean;
+
+    getVertex(vertexOrId: VertexId | V): V | null;
+
+    getVertexId(vertexOrId: V | VertexId): VertexId;
+
+    vertexSet(): Map<VertexId, V>;
+
+    addVertex(v: V): boolean;
+
+    removeVertex(vertexOrId: V | VertexId): boolean;
+
+    removeAllVertices(vertices: V[] | VertexId[]): boolean;
+
+    degreeOf(vertexOrId: V | VertexId): number;
+
+    edgesOf(vertexOrId: V | VertexId): E[];
+
+    hasEdge(src: V | VertexId, dest: V | VertexId): boolean;
+
+    getEdge(srcOrId: V | VertexId, destOrId: V | VertexId): E | null;
+
+    edgeSet(): E[];
+
+    addEdge(edge: E): boolean;
+
+    removeEdgeBetween(srcOrId: V | VertexId, destOrId: V | VertexId): E | null;
+
+    removeEdge(edge: E): E | null;
+
+    setEdgeWeight(srcOrId: V | VertexId, destOrId: V | VertexId, weight: number): boolean;
+
+    getMinPathBetween(v1: V | VertexId, v2: V | VertexId, isWeight?: boolean): V[] | null;
+
+    getNeighbors(vertexOrId: V | VertexId): V[];
+}
\ No newline at end of file
diff --git a/src/data-structures/interfaces/avl-tree.ts b/src/data-structures/interfaces/avl-tree.ts
new file mode 100644
index 0000000..693da49
--- /dev/null
+++ b/src/data-structures/interfaces/avl-tree.ts
@@ -0,0 +1 @@
+export {}
\ No newline at end of file
diff --git a/src/data-structures/interfaces/binary-tree.ts b/src/data-structures/interfaces/binary-tree.ts
new file mode 100644
index 0000000..2471ea0
--- /dev/null
+++ b/src/data-structures/interfaces/binary-tree.ts
@@ -0,0 +1,10 @@
+import {BinaryTreeNodeId} from '../types';
+import {BinaryTreeNode} from '../binary-tree';
+
+export interface IBinaryTreeNode<T> {
+    _createNode(id: BinaryTreeNodeId, val: T | null, count?: number): BinaryTreeNode<T> | null
+}
+
+export interface IBinaryTree<T> {
+    _createNode(id: BinaryTreeNodeId, val: T | null, count?: number): BinaryTreeNode<T> | null
+}
\ No newline at end of file
diff --git a/src/data-structures/interfaces/bst.ts b/src/data-structures/interfaces/bst.ts
new file mode 100644
index 0000000..693da49
--- /dev/null
+++ b/src/data-structures/interfaces/bst.ts
@@ -0,0 +1 @@
+export {}
\ No newline at end of file
diff --git a/src/data-structures/interfaces/directed-graph.ts b/src/data-structures/interfaces/directed-graph.ts
new file mode 100644
index 0000000..87399c6
--- /dev/null
+++ b/src/data-structures/interfaces/directed-graph.ts
@@ -0,0 +1,15 @@
+import {VertexId} from '../types';
+
+export interface IDirectedGraph<V, E> {
+    incomingEdgesOf(vertex: V): E[];
+
+    outgoingEdgesOf(vertex: V): E[];
+
+    inDegreeOf(vertexOrId: V | VertexId): number;
+
+    outDegreeOf(vertexOrId: V | VertexId): number;
+
+    getEdgeSrc(e: E): V | null;
+
+    getEdgeDest(e: E): V | null;
+}
\ No newline at end of file
diff --git a/src/data-structures/interfaces/doubly-linked-list.ts b/src/data-structures/interfaces/doubly-linked-list.ts
new file mode 100644
index 0000000..693da49
--- /dev/null
+++ b/src/data-structures/interfaces/doubly-linked-list.ts
@@ -0,0 +1 @@
+export {}
\ No newline at end of file
diff --git a/src/data-structures/interfaces/heap.ts b/src/data-structures/interfaces/heap.ts
new file mode 100644
index 0000000..693da49
--- /dev/null
+++ b/src/data-structures/interfaces/heap.ts
@@ -0,0 +1 @@
+export {}
\ No newline at end of file
diff --git a/src/data-structures/interfaces/index.ts b/src/data-structures/interfaces/index.ts
new file mode 100644
index 0000000..cf54b0e
--- /dev/null
+++ b/src/data-structures/interfaces/index.ts
@@ -0,0 +1,13 @@
+export * from './binary-tree';
+export * from './bst';
+export * from './avl-tree';
+export * from './segment-tree';
+export * from './tree-multiset';
+export * from './abstract-graph';
+export * from './directed-graph';
+export * from './undirected-graph';
+export * from './priority-queue';
+export * from './heap';
+export * from './singly-linked-list';
+export * from './doubly-linked-list';
+export * from './navigator';
\ No newline at end of file
diff --git a/src/data-structures/interfaces/navigator.ts b/src/data-structures/interfaces/navigator.ts
new file mode 100644
index 0000000..693da49
--- /dev/null
+++ b/src/data-structures/interfaces/navigator.ts
@@ -0,0 +1 @@
+export {}
\ No newline at end of file
diff --git a/src/data-structures/interfaces/priority-queue.ts b/src/data-structures/interfaces/priority-queue.ts
new file mode 100644
index 0000000..693da49
--- /dev/null
+++ b/src/data-structures/interfaces/priority-queue.ts
@@ -0,0 +1 @@
+export {}
\ No newline at end of file
diff --git a/src/data-structures/interfaces/segment-tree.ts b/src/data-structures/interfaces/segment-tree.ts
new file mode 100644
index 0000000..693da49
--- /dev/null
+++ b/src/data-structures/interfaces/segment-tree.ts
@@ -0,0 +1 @@
+export {}
\ No newline at end of file
diff --git a/src/data-structures/interfaces/singly-linked-list.ts b/src/data-structures/interfaces/singly-linked-list.ts
new file mode 100644
index 0000000..336ce12
--- /dev/null
+++ b/src/data-structures/interfaces/singly-linked-list.ts
@@ -0,0 +1 @@
+export {}
diff --git a/src/data-structures/interfaces/tree-multiset.ts b/src/data-structures/interfaces/tree-multiset.ts
new file mode 100644
index 0000000..693da49
--- /dev/null
+++ b/src/data-structures/interfaces/tree-multiset.ts
@@ -0,0 +1 @@
+export {}
\ No newline at end of file
diff --git a/src/data-structures/interfaces/undirected-graph.ts b/src/data-structures/interfaces/undirected-graph.ts
new file mode 100644
index 0000000..181f593
--- /dev/null
+++ b/src/data-structures/interfaces/undirected-graph.ts
@@ -0,0 +1,3 @@
+export interface IUNDirectedGraph<V, E> {
+
+}
\ No newline at end of file
diff --git a/src/data-structures/linked-list/doubly-linked-list.ts b/src/data-structures/linked-list/doubly-linked-list.ts
index 6e5a1de..cc24188 100644
--- a/src/data-structures/linked-list/doubly-linked-list.ts
+++ b/src/data-structures/linked-list/doubly-linked-list.ts
@@ -49,7 +49,7 @@ export class DoublyLinkedListNode<T = number> {
     }
 }
 
-export class DoublyLinkedList<T> {
+export class DoublyLinkedList<T = number> {
 
     /**
      * The constructor initializes the linked list with an empty head, tail, and length.
diff --git a/src/data-structures/linked-list/singly-linked-list.ts b/src/data-structures/linked-list/singly-linked-list.ts
index fb052b6..3f1b5b0 100644
--- a/src/data-structures/linked-list/singly-linked-list.ts
+++ b/src/data-structures/linked-list/singly-linked-list.ts
@@ -38,7 +38,7 @@ export class SinglyLinkedListNode<T = number> {
     }
 }
 
-export class SinglyLinkedList<T> {
+export class SinglyLinkedList<T = number> {
 
     /**
      * The constructor initializes the linked list with an empty head, tail, and length.
diff --git a/src/data-structures/priority-queue/max-priority-queue.ts b/src/data-structures/priority-queue/max-priority-queue.ts
index d123353..97a63e0 100644
--- a/src/data-structures/priority-queue/max-priority-queue.ts
+++ b/src/data-structures/priority-queue/max-priority-queue.ts
@@ -6,7 +6,8 @@
  * @license MIT License
  */
 import {PriorityQueue} from './priority-queue';
-import type {PriorityQueueOptions, SpecifyOptional} from '../types';
+import type {PriorityQueueOptions} from '../types';
+import {SpecifyOptional} from '../../utils';
 
 export class MaxPriorityQueue<T = number> extends PriorityQueue<T> {
     constructor(options?: Omit<PriorityQueueOptions<number>, 'comparator'>)
diff --git a/src/data-structures/priority-queue/min-priority-queue.ts b/src/data-structures/priority-queue/min-priority-queue.ts
index bd01c70..933c819 100644
--- a/src/data-structures/priority-queue/min-priority-queue.ts
+++ b/src/data-structures/priority-queue/min-priority-queue.ts
@@ -6,7 +6,8 @@
  * @license MIT License
  */
 import {PriorityQueue} from './priority-queue';
-import type {PriorityQueueOptions, SpecifyOptional} from '../types';
+import type {PriorityQueueOptions} from '../types';
+import {SpecifyOptional} from '../../utils';
 
 export class MinPriorityQueue<T = number> extends PriorityQueue<T> {
     constructor(options?: Omit<PriorityQueueOptions<number>, 'comparator'>)
diff --git a/src/data-structures/priority-queue/priority-queue.ts b/src/data-structures/priority-queue/priority-queue.ts
index ec6632e..c846708 100644
--- a/src/data-structures/priority-queue/priority-queue.ts
+++ b/src/data-structures/priority-queue/priority-queue.ts
@@ -30,10 +30,6 @@ export class PriorityQueue<T = number> {
         return this._nodes;
     }
 
-    protected set nodes(value: T[]) {
-        this._nodes = value;
-    }
-
     get size(): number {
         return this.nodes.length;
     }
@@ -137,7 +133,7 @@ export class PriorityQueue<T = number> {
      * The clear function clears the nodes array.
      */
     clear() {
-        this.nodes = [];
+        this._setNodes([]);
     }
 
     /**
@@ -231,6 +227,10 @@ export class PriorityQueue<T = number> {
         return visitedNode;
     }
 
+    protected _setNodes(value: T[]) {
+        this._nodes = value;
+    }
+
     protected readonly _comparator: PriorityQueueComparator<T> = (a: T, b: T) => {
         const aKey = a as unknown as number, bKey = b as unknown as number;
         return aKey - bKey;
diff --git a/src/data-structures/queue/deque.ts b/src/data-structures/queue/deque.ts
index 0190442..7db2a5d 100644
--- a/src/data-structures/queue/deque.ts
+++ b/src/data-structures/queue/deque.ts
@@ -16,7 +16,7 @@ export class Deque<T> extends DoublyLinkedList<T> {
 // O(1) time complexity of obtaining the value
 // O(n) time complexity of adding at the beginning and the end
 // todo tested slowest one
-export class ObjectDeque<T> {
+export class ObjectDeque<T = number> {
     constructor(capacity?: number) {
         if (capacity !== undefined) this._capacity = capacity;
     }
@@ -27,10 +27,6 @@ export class ObjectDeque<T> {
         return this._nodes;
     }
 
-    protected set nodes(value: { [p: number]: T }) {
-        this._nodes = value;
-    }
-
     private _capacity = Number.MAX_SAFE_INTEGER;
 
     get capacity(): number {
@@ -67,10 +63,6 @@ export class ObjectDeque<T> {
         return this._size;
     }
 
-    protected set size(value: number) {
-        this._size = value;
-    }
-
     addFirst(value: T) {
         if (this._size === 0) {
             const mid = Math.floor(this._capacity / 2);
@@ -129,6 +121,14 @@ export class ObjectDeque<T> {
     isEmpty() {
         return this._size <= 0;
     }
+
+    protected _seNodes(value: { [p: number]: T }) {
+        this._nodes = value;
+    }
+
+    protected _setSize(value: number) {
+        this._size = value;
+    }
 }
 
 // O(1) time complexity of obtaining the value
diff --git a/src/data-structures/queue/queue.ts b/src/data-structures/queue/queue.ts
index a709f14..239127c 100644
--- a/src/data-structures/queue/queue.ts
+++ b/src/data-structures/queue/queue.ts
@@ -3,7 +3,7 @@
  * @copyright Tyler Zeng <zrwusa@gmail.com>
  * @class
  */
-export class Queue<T> {
+export class Queue<T = number> {
     protected _nodes: T[];
     protected _offset: number;
 
diff --git a/src/data-structures/stack/stack.ts b/src/data-structures/stack/stack.ts
index 3ad714f..e2f54ba 100644
--- a/src/data-structures/stack/stack.ts
+++ b/src/data-structures/stack/stack.ts
@@ -3,7 +3,7 @@
  * @copyright Tyler Zeng <zrwusa@gmail.com>
  * @class
  */
-export class Stack<T> {
+export class Stack<T = number> {
     protected _elements: T[];
 
     /**
diff --git a/src/data-structures/types/abstract-graph.ts b/src/data-structures/types/abstract-graph.ts
index 6c6fc66..890442d 100644
--- a/src/data-structures/types/abstract-graph.ts
+++ b/src/data-structures/types/abstract-graph.ts
@@ -2,50 +2,3 @@ export type VertexId = string | number;
 export type DijkstraResult<V> =
     { distMap: Map<V, number>, preMap: Map<V, V | null>, seen: Set<V>, paths: V[][], minDist: number, minPath: V[] }
     | null;
-
-export interface IGraph<V, E> {
-
-    hasVertex(vertexOrId: V | VertexId): boolean;
-
-    getVertex(vertexOrId: VertexId | V): V | null;
-
-    getVertexId(vertexOrId: V | VertexId): VertexId;
-
-    vertexSet(): Map<VertexId, V>;
-
-    addVertex(v: V): boolean;
-
-    removeVertex(vertexOrId: V | VertexId): boolean;
-
-    removeAllVertices(vertices: V[] | VertexId[]): boolean;
-
-    degreeOf(vertexOrId: V | VertexId): number;
-
-    edgesOf(vertexOrId: V | VertexId): E[];
-
-    hasEdge(src: V | VertexId, dest: V | VertexId): boolean;
-
-    // hasEdge(e: E): boolean;
-
-    getEdge(srcOrId: V | VertexId, destOrId: V | VertexId): E | null;
-
-    // getAllEdges(src: V, dest: V): E[];
-
-    edgeSet(): E[];
-
-    addEdge(edge: E): boolean;
-
-    removeEdgeBetween(srcOrId: V | VertexId, destOrId: V | VertexId): E | null;
-
-    removeEdge(edge: E): E | null;
-
-    // removeAllEdges(v1: VertexId | V, v2: VertexId | V): (E | null)[];
-
-    // removeAllEdges(edges: E[] | [VertexId, VertexId]): boolean;
-
-    setEdgeWeight(srcOrId: V | VertexId, destOrId: V | VertexId, weight: number): boolean;
-
-    getMinPathBetween(v1: V | VertexId, v2: V | VertexId, isWeight?: boolean): V[] | null;
-
-    getNeighbors(vertexOrId: V | VertexId): V[];
-}
\ No newline at end of file
diff --git a/src/data-structures/types/avl-tree.ts b/src/data-structures/types/avl-tree.ts
index 3f0c154..c3511d5 100644
--- a/src/data-structures/types/avl-tree.ts
+++ b/src/data-structures/types/avl-tree.ts
@@ -1,6 +1,6 @@
 import {AVLTreeNode} from '../binary-tree';
 
-export interface AVLTreeDeleted<T> {
+export type AVLTreeDeleted<T> = {
     deleted: AVLTreeNode<T> | null;
     needBalanced: AVLTreeNode<T> | null;
 }
\ No newline at end of file
diff --git a/src/data-structures/types/directed-graph.ts b/src/data-structures/types/directed-graph.ts
index aea9be5..971b88d 100644
--- a/src/data-structures/types/directed-graph.ts
+++ b/src/data-structures/types/directed-graph.ts
@@ -1,18 +1,8 @@
-import {VertexId} from './abstract-graph';
-
-export interface IDirectedGraph<V, E> {
-    incomingEdgesOf(vertex: V): E[];
-
-    outgoingEdgesOf(vertex: V): E[];
-
-    inDegreeOf(vertexOrId: V | VertexId): number;
-
-    outDegreeOf(vertexOrId: V | VertexId): number;
-
-    getEdgeSrc(e: E): V | null;
-
-    getEdgeDest(e: E): V | null;
-}
-
 // 0 means unknown, 1 means visiting, 2 means visited;
-export type TopologicalStatus = 0 | 1 | 2;
\ No newline at end of file
+export type TopologicalStatus = 0 | 1 | 2;
+
+export enum TopologicalProperty {
+    VAL = 'VAL',
+    NODE = 'NODE',
+    ID = 'ID',
+}
\ No newline at end of file
diff --git a/src/data-structures/types/heap.ts b/src/data-structures/types/heap.ts
index 65cf926..389697a 100644
--- a/src/data-structures/types/heap.ts
+++ b/src/data-structures/types/heap.ts
@@ -1,4 +1,4 @@
-export interface HeapOptions<T> {
+export type HeapOptions<T> = {
     priority?: (element: T) => number;
     // TODO there is an idea that support chaining which is for conveniently using the data structure
     // isChaining? : boolean
diff --git a/src/data-structures/types/index.ts b/src/data-structures/types/index.ts
index 7b19e5d..3a58bb1 100644
--- a/src/data-structures/types/index.ts
+++ b/src/data-structures/types/index.ts
@@ -9,5 +9,4 @@ export * from './priority-queue';
 export * from './heap';
 export * from './singly-linked-list';
 export * from './doubly-linked-list';
-export * from './navigator';
-export * from '../../utils/types/utils';
\ No newline at end of file
+export * from './navigator';
\ No newline at end of file
diff --git a/src/data-structures/types/navigator.ts b/src/data-structures/types/navigator.ts
index 0676678..231f6b9 100644
--- a/src/data-structures/types/navigator.ts
+++ b/src/data-structures/types/navigator.ts
@@ -1,7 +1,7 @@
 export type Direction = 'up' | 'right' | 'down' | 'left';
 export type Turning = { [key in Direction]: Direction };
 
-export interface NavigatorParams<T> {
+export type NavigatorParams<T> = {
     matrix: T[][],
     turning: Turning,
     onMove: (cur: [number, number]) => void
diff --git a/src/data-structures/types/priority-queue.ts b/src/data-structures/types/priority-queue.ts
index 48e398a..3fe3b75 100644
--- a/src/data-structures/types/priority-queue.ts
+++ b/src/data-structures/types/priority-queue.ts
@@ -1,6 +1,6 @@
 export type PriorityQueueComparator<T> = (a: T, b: T) => number;
 
-export interface PriorityQueueOptions<T> {
+export type PriorityQueueOptions<T> = {
     nodes?: T[];
     isFix?: boolean;
     comparator: PriorityQueueComparator<T>;
diff --git a/tests/unit/data-structures/graph/directed-graph.test.ts b/tests/unit/data-structures/graph/directed-graph.test.ts
index b364c8c..83f4cd6 100644
--- a/tests/unit/data-structures/graph/directed-graph.test.ts
+++ b/tests/unit/data-structures/graph/directed-graph.test.ts
@@ -59,7 +59,7 @@ describe('DirectedGraph Operation Test', () => {
         graph.addEdge(edgeBC);
 
         const topologicalOrder = graph.topologicalSort();
-        if (topologicalOrder) expect(topologicalOrder.map(v => v.id)).toEqual(['A', 'B', 'C']);
+        if (topologicalOrder) expect(topologicalOrder.map(v => v instanceof DirectedVertex ? v.id: '')).toEqual(['A', 'B', 'C']);
     });
 });
 
@@ -168,9 +168,9 @@ describe('DirectedGraph Test2 operations', () => {
         expect(sorted).toBeInstanceOf(Array);
         if (sorted && sorted.length > 0) {
             expect(sorted.length).toBe(9);
-            expect(sorted[0].data).toBe('data9');
-            expect(sorted[3].data).toBe('data6');
-            expect(sorted[8].id).toBe(1);
+            if (sorted[0] instanceof MyVertex) expect(sorted[0].data).toBe('data9');
+            sorted[3] instanceof MyVertex && expect(sorted[3].data).toBe('data6');
+            sorted[8] instanceof MyVertex && expect(sorted[8].id).toBe(1);
         }
 
     });