feat(graph) breadth-first search

Author: amejiarosario

lib/data-structures/graphs/graph.js

@@ -92,9 +92,32 @@ class Graph {
     return [sourceNode, targetNode];
   }
 
+  /**
+   * Depth-first search
+   * Use a stack to visit nodes (LIFO)
+   * @param {Node} first node to start the dfs
+   */
   *dfs(first) {
+    yield* this._graphSearch(first, Stack);
+  }
+
+  /**
+   * Depth-first search
+   * Use a queue to visit nodes (FIFO)
+   * @param {Node} first node to start the dfs
+   */
+  *bfs(first) {
+    yield* this._graphSearch(first, Queue);
+  }
+
+  /**
+   *
+   * @param {Node} first
+   * @param {Stack|Queue} dsType Stack for DFS or Queue for BFS
+   */
+  *_graphSearch(first, dsType = Stack) {
     const visited = new Map();
-    const visitList = new Stack();
+    const visitList = new dsType();
 
     visitList.add(first);
 

lib/data-structures/graphs/graph.spec.js

@@ -96,28 +96,39 @@ describe('Graph', () => {
     });
   });
 
-  describe('#dfs', () => {
+  describe('Graph Search', () => {
     let first;
 
     beforeEach(() => {
-      const [a] = graph.addEdge(0, 1);
-      first = a;
-      graph.addEdge(0, 4);
       graph.addEdge(0, 5);
+      graph.addEdge(0, 4);
+      [first] = graph.addEdge(0, 1);
 
-      graph.addEdge(1, 3);
       graph.addEdge(1, 4);
+      graph.addEdge(1, 3);
 
       graph.addEdge(2, 1);
 
-      graph.addEdge(3, 2);
       graph.addEdge(3, 4);
+      graph.addEdge(3, 2);
     });
 
-    it('should visit nodes using depth-first search', () => {
-      const visitedOrder = Array.from(graph.dfs(first)).map(v => v.value);
-      // expect(visitedOrder).toEqual([0, 1, 3, 2, 4, 5]);
-      expect(visitedOrder).toEqual([0, 5, 4, 1, 3, 2]);
+    describe('#dfs', () => {
+
+      it('should visit nodes using depth-first search', () => {
+        const visitedOrder = Array.from(graph.dfs(first)).map(v => v.value);
+        expect(visitedOrder).toEqual([0, 1, 3, 2, 4, 5]);
+      });
+    });
+
+    describe('#bfs', () => {
+
+      it('should visit nodes using breadth-first search', () => {
+        const visitedOrder = Array.from(graph.bfs(first)).map(v => v.value);
+        expect(visitedOrder).toEqual([0, 5, 4, 1, 3, 2]);
+      });
     });
   });
+
+
 });

lib/data-structures/queues/queue.js

@@ -31,6 +31,13 @@ class Queue {
   get size() {
     return this.input.size;
   }
+
+  /**
+   * Return true if is empty false otherwise true
+   */
+  isEmpty() {
+    return !this.input.size;
+  }
 }
 
 // Aliases

lib/data-structures/queues/queue.spec.js

@@ -1,4 +1,4 @@
-const Queue = require('./queue-2.js');
+const Queue = require('./queue.js');
 
 describe('Queue', function () {
   let queue;
@@ -34,4 +34,16 @@ describe('Queue', function () {
       expect(queue.remove()).toBe(undefined);
     })
   });
+
+  describe('#isEmpty', () => {
+    it('should return true when empty', () => {
+      expect(queue.isEmpty()).toBe(true);
+    });
+
+    it('should return false when not empty', () => {
+      queue.add('a');
+      // expect(queue.size).toBe(1);
+      expect(queue.isEmpty()).toBe(false);
+    });
+  });
 });