Merge pull request #555 from rodigu/breadth-first-search

Node Neighbors

Graphs/NodeNeighbors.js

@@ -0,0 +1,40 @@
+// https://en.wikipedia.org/wiki/Neighbourhood_(graph_theory)
+
+class Graph {
+  // Generic graph: the algorithm works regardless of direction or weight
+  constructor () {
+    this.edges = []
+  }
+
+  addEdge (node1, node2) {
+    // Adding edges to the graph
+    this.edges.push({
+      node1,
+      node2
+    })
+  }
+
+  nodeNeighbors (node) {
+    // Returns an array with all of the node neighbors
+    const neighbors = new Set()
+    for (const edge of this.edges) {
+      // Checks if they have an edge between them and if the neighbor is not
+      // already in the neighbors array
+      if (edge.node1 === node && !(neighbors.has(edge.node2))) {
+        neighbors.add(edge.node2)
+      } else if (edge.node2 === node && !(neighbors.has(edge.node1))) {
+        neighbors.add(edge.node1)
+      }
+    }
+    return neighbors
+  }
+}
+
+(() => {
+  const graph = new Graph()
+  graph.addEdge(1, 2)
+  graph.addEdge(2, 3)
+  graph.addEdge(3, 5)
+  graph.addEdge(1, 5)
+  console.log(graph.nodeNeighbors(1))
+})()