fix: bug fixed #58, DirectedGraph.getCycles returns an inexisting cycle. feat: hasValue method for HashMap.

src/data-structures/graph/abstract-graph.ts

@@ -1086,15 +1086,33 @@ export abstract class AbstractGraph<
     }
 
     const cycles: Map<number, VO[]> = new Map();
-    if (needCycles) {
-      let SCCs: Map<number, VO[]> = new Map();
-      if (SCCs.size < 1) {
-        SCCs = getSCCs();
-      }
 
-      SCCs.forEach((SCC, low) => {
-        if (SCC.length > 1) {
-          cycles.set(low, SCC);
+    if (needCycles) {
+      const visitedMap: Map<VO, boolean> = new Map();
+      const stack: VO[] = [];
+      const findCyclesDFS = (cur: VO, parent: VO | undefined) => {
+        visitedMap.set(cur, true);
+        stack.push(cur);
+
+        const neighbors = this.getNeighbors(cur);
+
+        for (const neighbor of neighbors) {
+          if (!visitedMap.get(neighbor)) {
+            findCyclesDFS(neighbor, cur);
+          } else if (stack.includes(neighbor) && neighbor !== parent) {
+            const cycleStartIndex = stack.indexOf(neighbor);
+            const cycle = stack.slice(cycleStartIndex);
+            const cycleLow = Math.min(...cycle.map(v => dfnMap.get(v) || Infinity));
+            cycles.set(cycleLow, cycle);
+          }
+        }
+
+        stack.pop();
+      };
+
+      vertexMap.forEach(v => {
+        if (!visitedMap.get(v)) {
+          findCyclesDFS(v, undefined);
         }
       });
     }

src/data-structures/hash/hash-map.ts

@@ -411,6 +411,13 @@ export class LinkedHashMap<K = any, V = any> extends IterableEntryBase<K, V> {
     }
   }
 
+  hasValue(value: V): boolean {
+    for (const [, elementValue] of this) {
+      if (elementValue === value) return true;
+    }
+    return false;
+  }
+
   setMany(entries: Iterable<[K, V]>): void {
     for (const entry of entries) {
       const [key, value] = entry;

src/data-structures/queue/queue.ts

@@ -188,7 +188,7 @@ export class Queue<E = any> extends IterableElementBase<E> {
    * @param {E} value - The value parameter represents the value that you want to add to the queue.
    */
   enqueue(value: E) {
-    this.push(value);
+    return this.push(value);
   }
 
   /**

test/unit/data-structures/graph/directed-graph.test.ts

@@ -588,7 +588,7 @@ describe('cycles, strongly connected components, bridges, articular points in Di
   const cutVertexes = graph.getCutVertexes();
   const dfnMap = graph.getDFNMap();
   const lowMap = graph.getLowMap();
-  expect(cycles.size).toBe(1);
+  expect(cycles.size).toBe(2);
   expect(scCs.size).toBe(5);
   expect(bridges.length).toBe(4);
   expect(cutVertexes.length).toBe(4);
@@ -673,3 +673,24 @@ describe('DirectedGraph iterative Methods', () => {
   })
 });
 
+describe('DirectedGraph getCycles', () => {
+  test('should getCycles return correct result', () => {
+    const graph = new DirectedGraph();
+    graph.addVertex('A');
+    graph.addVertex('B');
+    graph.addVertex('C');
+    graph.addVertex('D');
+    graph.addVertex('E');
+    graph.addEdge('A', 'B');
+    graph.addEdge('A', 'C');
+    graph.addEdge('B', 'D');
+    graph.addEdge('C', 'D');
+    graph.addEdge('D', 'E');
+    graph.addEdge('E', 'B');
+    const cycles = graph.getCycles();
+    expect(cycles.size).toBe(1);
+
+    console.log(Array.from(cycles.values()));
+  })
+})
+

test/unit/data-structures/graph/undirected-graph.test.ts

@@ -237,7 +237,7 @@ describe('cycles, strongly connected components, bridges, articular points in Un
   const cutVertexes = graph.getCutVertexes();
   const dfnMap = graph.getDFNMap();
   const lowMap = graph.getLowMap();
-  expect(cycles.size).toBe(1);
+  expect(cycles.size).toBe(2);
   expect(scCs.size).toBe(5);
   expect(bridges.length).toBe(4);
   expect(cutVertexes.length).toBe(4);
@@ -260,4 +260,24 @@ it("Should return Infinity if dest is not found", () => {
 
   const minCost01 = graph.getMinCostBetween(0, 1, true);
   expect(minCost01).toBe(1);
-});
+});
+
+describe('UndirectedGraph getCycles', () => {
+  test('should getCycles return correct result', () => {
+    const graph = new UndirectedGraph();
+    graph.addVertex('A');
+    graph.addVertex('B');
+    graph.addVertex('C');
+    graph.addVertex('D');
+    graph.addVertex('E');
+    graph.addEdge('A', 'B');
+    graph.addEdge('A', 'C');
+    graph.addEdge('B', 'D');
+    graph.addEdge('C', 'D');
+    graph.addEdge('D', 'E');
+    graph.addEdge('E', 'B');
+    const cycles = graph.getCycles();
+    expect(cycles.size).toBe(2);
+    console.log(Array.from(cycles.values()));
+  })
+})