Added Bellman Ford Negative Cycle implementation and test file with prettier code

Author: Mayank29903

Graphs/BellmanFordNegativeCycle.js

@@ -10,18 +10,17 @@ function bellmanFordNegativeCycle(graph, vertices, start) {
   const dist = new Array(vertices).fill(Infinity)
   dist[start] = 0
 
-  // relax all edges (V - 1) times
   for (let i = 0; i < vertices - 1; i++) {
-    for (let [u, v, w] of graph) {
+    for (const [u, v, w] of graph) {
       if (dist[u] !== Infinity && dist[u] + w < dist[v]) {
         dist[v] = dist[u] + w
       }
     }
   }
 
-  // check for negative cycle
-  for (let [u, v, w] of graph) {
+  for (const [u, v, w] of graph) {
     if (dist[u] !== Infinity && dist[u] + w < dist[v]) {
+      // A shorter path found after V-1 iterations means a negative cycle exists
       return { hasNegativeCycle: true, dist }
     }
   }