Merge pull request #62 from sourav-naskar/main

added Bellman-Ford Algorithm

Author: gantavyamalviya

CPP/graph_tree/Bellman-Ford-Algorithm.cpp

@@ -0,0 +1,62 @@
+#include<bits/stdc++.h>
+using namespace std;
+struct node {
+    int u;
+    int v;
+    int wt; 
+    node(int first, int second, int weight) {
+        u = first;
+        v = second;
+        wt = weight;
+    }
+};
+
+int main(){
+    int N=6,m=7;
+    vector<node> edges; 
+	edges.push_back(node(0,1,5));
+	edges.push_back(node(1,2,-2));
+	edges.push_back(node(1,5,-3));
+	edges.push_back(node(2,4,3));
+	edges.push_back(node(3,2,6));
+	edges.push_back(node(3,4,-2));
+	edges.push_back(node(5,3,1));
+    int src=0;
+    int inf = 10000000; 
+    vector<int> dist(N, inf); 
+    dist[src] = 0; 
+    for(int i = 1;i<=N-1;i++) {
+        for(auto it: edges) {
+            if(dist[it.u] + it.wt < dist[it.v]) {
+                dist[it.v] = dist[it.u] + it.wt; 
+            }
+        }
+    }
+
+    int fl = 0; 
+    for(auto it: edges) {
+        if(dist[it.u] + it.wt < dist[it.v]) {
+            cout << -1; 
+            fl = 1; 
+            break; 
+        }
+    }
+    
+    if(!fl) {
+        for(int i = 0;i<N;i++) {
+            cout << dist[i]<<" ";
+        }
+    }
+    return 0;
+}
+
+/*
+Output:
+0 5 3 3 1 2
+
+Time Complexity: O(N*E). We check E edges N times
+
+Space Complexity: O(N). Distance Array
+*/
+
+//contributed by Sourav Naskar