merge: Add Graph3 (add DFS in Iterative Way) (#944)

* Add Graph3 (add DFS in Iterative Way)

* Remove example code and add test code (Graph3)

* Remove redundant code (like return undefined)

Data-Structures/Graph/Graph3.js

@@ -0,0 +1,108 @@
+class Graph {
+  constructor () {
+    this.adjacencyObject = {}
+  }
+
+  addVertex (vertex) {
+    if (!this.adjacencyObject[vertex]) this.adjacencyObject[vertex] = []
+  }
+
+  addEdge (vertex1, vertex2) {
+    this.adjacencyObject[vertex1].push(vertex2)
+    this.adjacencyObject[vertex2].push(vertex1)
+  }
+
+  removeEdge (vertex1, vertex2) {
+    this.adjacencyObject[vertex1] = this.adjacencyObject[vertex1].filter(
+      (v) => v !== vertex2
+    )
+    this.adjacencyObject[vertex2] = this.adjacencyObject[vertex2].filter(
+      (v) => v !== vertex1
+    )
+  }
+
+  removeVertex (vertex) {
+    while (this.adjacencyObject[vertex].length) {
+      const adjacentVertex = this.adjacencyObject[vertex].pop()
+      this.removeEdge(vertex, adjacentVertex)
+    }
+  }
+
+  /**
+   * Return DFS (Depth First Search) List Using Recursive Method
+   */
+  DFS (start) {
+    if (!start) return null
+
+    const result = []
+    const visited = {}
+    const adjacencyObject = this.adjacencyObject
+
+    function dfs (vertex) {
+      if (!vertex) return null
+      visited[vertex] = true
+      result.push(vertex)
+      adjacencyObject[vertex].forEach((neighbor) => {
+        if (!visited[neighbor]) {
+          dfs(neighbor)
+        }
+      })
+    }
+
+    dfs(start)
+    return result
+  }
+
+  /**
+   * Return DFS(Depth First Search) List Using Iteration
+   */
+  DFSIterative (start) {
+    if (!start) return null
+
+    const stack = [start]
+    const visited = {}
+    visited[start] = true
+
+    const result = []
+    let currentVertex
+
+    while (stack.length) {
+      currentVertex = stack.pop()
+      result.push(currentVertex)
+
+      this.adjacencyObject[currentVertex].forEach((neighbor) => {
+        if (!visited[neighbor]) {
+          visited[neighbor] = true
+          stack.push(neighbor)
+        }
+      })
+    }
+    return result
+  }
+
+  BFS (start) {
+    if (!start) return null
+
+    const queue = [start]
+    const visited = {}
+    visited[start] = true
+
+    let currentVertex
+    const result = []
+
+    while (queue.length) {
+      currentVertex = queue.shift()
+      result.push(currentVertex)
+
+      this.adjacencyObject[currentVertex].forEach((neighbor) => {
+        if (!visited[neighbor]) {
+          visited[neighbor] = true
+          queue.push(neighbor)
+        }
+      })
+    }
+    return result
+  }
+}
+
+export { Graph }

Data-Structures/Graph/test/Graph3.test.js

@@ -0,0 +1,75 @@
+import { Graph } from '../Graph3'
+
+describe('Test Graph3', () => {
+  const g = new Graph()
+
+  // Add Vertices
+  g.addVertex('A')
+  g.addVertex('B')
+  g.addVertex('C')
+  g.addVertex('D')
+  g.addVertex('E')
+  g.addVertex('F')
+
+  // Add Edges
+  g.addEdge('A', 'B')
+  g.addEdge('A', 'C')
+  g.addEdge('B', 'D')
+  g.addEdge('C', 'E')
+  g.addEdge('D', 'E')
+  g.addEdge('D', 'F')
+  g.addEdge('E', 'F')
+
+  /**
+   * A - B - D
+   * |      / \
+   * C - - E - F
+   *
+   * DFS(Iterative): A-C-E-F-D-B
+   * DFS(Recursive): A-B-D-E-C-F
+   * BFS: A-B-C-D-E-F
+   */
+  it('Check iterative DFS List', () => {
+    const iterativeDFSList = g.DFSIterative('A')
+    expect(iterativeDFSList).toEqual(['A', 'C', 'E', 'F', 'D', 'B'])
+  })
+
+  it('Check recursive DFS List', () => {
+    const recursiveDFSList = g.DFS('A')
+    expect(recursiveDFSList).toEqual(['A', 'B', 'D', 'E', 'C', 'F'])
+  })
+
+  it('Check BFS List', () => {
+    const BFSList = g.BFS('A')
+    expect(BFSList).toEqual(['A', 'B', 'C', 'D', 'E', 'F'])
+  })
+
+  /**
+   * Test After Remove 'B' Vertex
+   * A       D
+   * |      / \
+   * C - - E - F
+   *
+   * DFS(Iterative): A-C-E-F-D
+   * DFS(Recursive): A-C-E-D-F
+   * BFS: A-C-E-D-F
+   */
+
+  it('Check iterative DFS List After Removing Vertex B', () => {
+    g.removeVertex('B')
+    const iterativeDFSList = g.DFSIterative('A')
+    expect(iterativeDFSList).toEqual(['A', 'C', 'E', 'F', 'D'])
+  })
+
+  it('Check recursive DFS List After Removing Vertex B', () => {
+    g.removeVertex('B')
+    const recursiveDFSList = g.DFS('A')
+    expect(recursiveDFSList).toEqual(['A', 'C', 'E', 'D', 'F'])
+  })
+
+  it('Check BFS List After Removing Vertex B', () => {
+    g.removeVertex('B')
+    const BFSList = g.BFS('A')
+    expect(BFSList).toEqual(['A', 'C', 'E', 'D', 'F'])
+  })
+})