Update Graph.

Author: trekhleb

src/data-structures/graph/Graph.js

@@ -110,6 +110,12 @@ export default class Graph {
     return null;
   }
 
+  getWeight() {
+    return this.getAllEdges().reduce((weight, graphEdge) => {
+      return weight + graphEdge.weight;
+    }, 0);
+  }
+
   toString() {
     return Object.keys(this.vertices).toString();
   }

src/data-structures/graph/GraphEdge.js

@@ -4,7 +4,7 @@ export default class GraphEdge {
    * @param {GraphVertex} endVertex
    * @param {number} [weight=1]
    */
-  constructor(startVertex, endVertex, weight = 1) {
+  constructor(startVertex, endVertex, weight = 0) {
     this.startVertex = startVertex;
     this.endVertex = endVertex;
     this.weight = weight;

src/data-structures/graph/__test__/Graph.test.js

@@ -174,4 +174,48 @@ describe('Graph', () => {
     expect(edges[0]).toEqual(edgeAB);
     expect(edges[1]).toEqual(edgeBC);
   });
+
+  it('should calculate total graph weight for default graph', () => {
+    const graph = new Graph();
+
+    const vertexA = new GraphVertex('A');
+    const vertexB = new GraphVertex('B');
+    const vertexC = new GraphVertex('C');
+    const vertexD = new GraphVertex('D');
+
+    const edgeAB = new GraphEdge(vertexA, vertexB);
+    const edgeBC = new GraphEdge(vertexB, vertexC);
+    const edgeCD = new GraphEdge(vertexC, vertexD);
+    const edgeAD = new GraphEdge(vertexA, vertexD);
+
+    graph
+      .addEdge(edgeAB)
+      .addEdge(edgeBC)
+      .addEdge(edgeCD)
+      .addEdge(edgeAD);
+
+    expect(graph.getWeight()).toBe(0);
+  });
+
+  it('should calculate total graph weight for weighted graph', () => {
+    const graph = new Graph();
+
+    const vertexA = new GraphVertex('A');
+    const vertexB = new GraphVertex('B');
+    const vertexC = new GraphVertex('C');
+    const vertexD = new GraphVertex('D');
+
+    const edgeAB = new GraphEdge(vertexA, vertexB, 1);
+    const edgeBC = new GraphEdge(vertexB, vertexC, 2);
+    const edgeCD = new GraphEdge(vertexC, vertexD, 3);
+    const edgeAD = new GraphEdge(vertexA, vertexD, 4);
+
+    graph
+      .addEdge(edgeAB)
+      .addEdge(edgeBC)
+      .addEdge(edgeCD)
+      .addEdge(edgeAD);
+
+    expect(graph.getWeight()).toBe(10);
+  });
 });

src/data-structures/graph/__test__/GraphEdge.test.js

@@ -10,7 +10,7 @@ describe('GraphEdge', () => {
     expect(edge.getKey()).toBe('A_B');
     expect(edge.startVertex).toEqual(startVertex);
     expect(edge.endVertex).toEqual(endVertex);
-    expect(edge.weight).toEqual(1);
+    expect(edge.weight).toEqual(0);
   });
 
   it('should create graph edge with predefined weight', () => {