From e9d54779fd6f54b52070cffc7ea2d5dcec1d520a Mon Sep 17 00:00:00 2001
From: Yatin <yatinkathuria74@gmail.com>
Date: Thu, 25 Nov 2021 23:48:16 +0530
Subject: [PATCH] Modify Graph bfs method

---
 Data-Structures/Graph/Graph.js | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/Data-Structures/Graph/Graph.js b/Data-Structures/Graph/Graph.js
index c7b234526f..2b7056fdb2 100644
--- a/Data-Structures/Graph/Graph.js
+++ b/Data-Structures/Graph/Graph.js
@@ -39,21 +39,19 @@ class Graph {
    * @param {number} source The source vertex to start BFS.
    */
   bfs (source, output = value => console.log(value)) {
-    const queue = []
+    const queue = [[source, 0]] // level of source is 0
     const visited = new Set()
-    queue.unshift([source, 0]) // level of source is 0
-    visited.add(source)
+
     while (queue.length) {
-      const front = queue[0]
-      const node = front[0]
-      const level = front[1]
-      queue.shift() // remove the front of the queue
+      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]) {
-        if (!visited.has(next)) { // not visited
-          queue.unshift([next, level + 1]) // level 1 more than current
-          visited.add(next)
-        }
+        queue.push([next, level + 1]) // level 1 more than current
       }
     }
   }