Added Bellman Ford Algorithm in CPP

Bellman Ford Algorithm.cpp

@@ -0,0 +1,94 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+struct node{
+    int u;
+    int v;
+    int wt;
+    node(int a,int b,int w)
+    {
+        u=a;
+        v=b;
+        wt=w;
+    }
+
+};
+
+void BellmanFord(int src,int n,vector<node> adj)
+{
+
+    vector<int> distance(n+1,100000);
+    distance[src]=0;
+
+    int i,j;
+
+    // Here, Relax all the edges n-1 times as max distance between two nodes in a graph can be n-1
+    for(i=0;i<n-1;i++)
+    {
+        for(auto it: adj)
+        {
+            int p=it.u;
+            int q=it.v;
+            int weight = it.wt;
+
+            if(distance[p]+weight<distance[q])
+            {
+                distance[q] = distance[p]+weight;
+            }
+        }
+    }
+
+    int flag=0;
+
+// This loop is for checking the negative cycle in graph
+    for(auto it: adj)
+    {
+        int p=it.u;
+        int q=it.v;
+        int weight = it.wt;
+
+        if(distance[p]+weight<distance[q])
+        {
+            distance[q] = distance[p]+weight;
+            flag=1;
+            break;
+        }
+    }
+
+    // If cycle present, then print negative cycle present , else print the distances of each node
+    if(flag) 
+    {
+        cout<<"Negative Cycle present";
+        return;
+    }
+
+    for(i=1;i<=n;i++) cout<<distance[i]<<" ";
+
+    // Time Complexity - O((V-1)*E) = O(V*E) 
+    // Space Complexity - O(V) (distance)
+}
+
+int main()
+{
+    #ifndef ONLINE_JUDGE
+    freopen("input.txt", "r", stdin);
+    freopen("output.txt", "w", stdout);
+    #endif
+    int n,edges,i,a,b,wt;
+    cin>>n>>edges;
+
+    vector<node> adj;
+
+    for(i=0;i<edges;i++)
+    {
+        cin>>a>>b>>wt;
+        adj.push_back(node(a,b,wt));
+        adj.push_back(node(b,a,wt)); // This is for the undirected graph else not needed for directed graph
+    }
+
+    // for(auto x: adj) cout<<x.u<<" ";
+
+    BellmanFord(1,n,adj);
+
+    return 0;
+}