feat: Added new graphs algorithms with doc strings

Graphs/Graph.js

@@ -0,0 +1,115 @@
+class Graph {
+  constructor() {
+    this.adjacencyMap = {}
+  }
+
+  addVertex(vertex) {
+    this.adjacencyMap[vertex] = []
+  }
+
+  containsVertex(vertex) {
+    return typeof this.adjacencyMap[vertex] !== 'undefined'
+  }
+
+  addEdge(vertex1, vertex2) {
+    if (this.containsVertex(vertex1) && this.containsVertex(vertex2)) {
+      this.adjacencyMap[vertex1].push(vertex2)
+      this.adjacencyMap[vertex2].push(vertex1)
+    }
+  }
+
+/**
+   * Prints the graph using the given output function.
+   *
+   * @param {function(value)} output The output function to use.
+   */
+
+  printGraph(output = (value) => console.log(value)) {
+    const keys = Object.keys(this.adjacencyMap)
+    for (const i of keys) {
+      const values = this.adjacencyMap[i]
+      let vertex = ''
+      for (const j of values) {
+        vertex += j + ' '
+      }
+      output(i + ' -> ' + vertex)
+    }
+  }
+
+  /**
+   * Prints the Breadth first traversal of the graph from source.
+   *
+   * @param {number} source The source vertex to start BFS.
+   * @param {function(value)} output The output function to use.
+   */
+
+  bfs(source, output = (value) => console.log(value)) {
+    const queue = [[source, 0]] // level of source is 0
+    const visited = new Set()
+
+    while (queue.length) {
+      const [node, level] = queue.shift() // remove the front of the queue
+      if (visited.has(node)) {
+        // visited
+        continue
+      }
+
+      visited.add(node)
+      output(`Visited node ${node} at level ${level}.`)
+      for (const next of this.adjacencyMap[node]) {
+        queue.push([next, level + 1]) // level 1 more than current
+      }
+    }
+  }
+
+  /**
+   * Prints the Depth first traversal of the graph from source.
+   *
+   * @param {number} source The source vertex to start DFS.
+   * @param {function(value)} output The output function to use.
+   */
+
+  dfs(source, visited = new Set(), output = (value) => console.log(value)) {
+    if (visited.has(source)) {
+      // visited
+      return
+    }
+
+    output(`Visited node ${source}`)
+    visited.add(source)
+    for (const neighbour of this.adjacencyMap[source]) {
+      this.dfs(neighbour, visited, output)
+    }
+  }
+}
+
+const example = () => {
+  const g = new Graph()
+  g.addVertex(1)
+  g.addVertex(2)
+  g.addVertex(3)
+  g.addVertex(4)
+  g.addVertex(5)
+  g.addEdge(1, 2)
+  g.addEdge(1, 3)
+  g.addEdge(2, 4)
+  g.addEdge(2, 5)
+
+  // Graph
+  // 1 -> 2 3
+  // 2 -> 1 4 5
+  // 3 -> 1
+  // 4 -> 2
+  // 5 -> 2
+
+  // Printing the adjacency list
+  // g.printGraph()
+
+  // Breadth first search at node 1
+  g.bfs(1)
+
+  // Depth first search at node 1
+  g.dfs(1)
+}
+
+export { Graph, example }

Graphs/Graph2.js

@@ -0,0 +1,71 @@
+// create a graph class
+class Graph {
+  // defining vertex array and
+  // adjacent list
+
+ /**
+ * Create a graph with the number of vertices
+ * @param {number} noOfVertices the number of vertices of the graph
+  */ 
+  constructor(noOfVertices) {
+    this.noOfVertices = noOfVertices
+    this.AdjList = new Map()
+  }
+
+  // functions to be implemented
+
+  // addVertex(v)
+  // addEdge(v, w)
+  // printGraph()
+
+  // bfs(v)
+  // dfs(v)
+
+  // add vertex to the graph
+  addVertex(v) {
+    // initialize the adjacent list with a
+    // null array
+
+    this.AdjList.set(v, [])
+  }
+
+  // add edge to the graph
+  addEdge(v, w) {
+    // get the list for vertex v and put the
+    // vertex w denoting edge between v and w
+    this.AdjList.get(v).push(w)
+
+    // Since graph is undirected,
+    // add an edge from w to v also
+    this.AdjList.get(w).push(v)
+  }
+
+  // Prints the vertex and adjacency list
+
+/**
+ * @param {function(value)}  output The output function use 
+ */
+  printGraph(output = (value) => console.log(value)) {
+    // get all the vertices
+    const getKeys = this.AdjList.keys()
+
+    // iterate over the vertices
+    for (const i of getKeys) {
+      // get the corresponding adjacency list
+      // for the vertex
+      const getValues = this.AdjList.get(i)
+      let conc = ''
+
+      // iterate over the adjacency list
+      // concatenate the values into a string
+      for (const j of getValues) {
+        conc += j + ' '
+      }
+
+      // print the vertex and its adjacency list
+      output(i + ' -> ' + conc)
+    }
+  }
+}
+
+export { Graph }

Graphs/Graph3.js

@@ -0,0 +1,126 @@
+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
+   *
+   * @param {number} start The start vertex.
+   * @returns {Array<number>} The DFS list.
+   *
+   */
+
+  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
+   *
+   * @param {number} start The start vertex.
+   * @returns {Array<number>} The DFS list.
+   */
+
+
+  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
+  }
+
+/**
+   * Return BFS (Breadth First Search) List
+   *
+   * @param {number} start The start vertex.
+   * @returns {Array<number>} The BFS list.
+*/
+
+  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 }