BellmanFord.cpp

#include <bits/stdc++.h> 

struct Edge { 
	int src, dest, weight; 
}; 
 
struct Graph { 

	int V, E; 

	
	struct Edge* edge; 
}; 


struct Graph* createGraph(int V, int E) 
{ 
	struct Graph* graph = new Graph; 
	graph->V = V; 
	graph->E = E; 
	graph->edge = new Edge[E]; 
	return graph; 
} 


void printArr(int dist[], int n) 
{ 
	printf("Vertex Distance from Source\n"); 
	for (int i = 0; i < n; ++i) 
		printf("%d \t\t %d\n", i, dist[i]); 
} 

void BellmanFord(struct Graph* graph, int src) 
{ 
	int V = graph->V; 
	int E = graph->E; 
	int dist[V]; 


	for (int i = 0; i < V; i++) 
		dist[i] = INT_MAX; 
	dist[src] = 0; 


	for (int i = 1; i <= V - 1; i++) { 
		for (int j = 0; j < E; j++) { 
			int u = graph->edge[j].src; 
			int v = graph->edge[j].dest; 
			int weight = graph->edge[j].weight; 
			if (dist[u] != INT_MAX && dist[u] + weight < dist[v]) 
				dist[v] = dist[u] + weight; 
		} 
	} 

	 
	for (int i = 0; i < E; i++) { 
		int u = graph->edge[i].src; 
		int v = graph->edge[i].dest; 
		int weight = graph->edge[i].weight; 
		if (dist[u] != INT_MAX && dist[u] + weight < dist[v]) { 
			printf("Graph contains negative weight cycle"); 
			return;  
		} 
	} 

	printArr(dist, V); 

	return; 
} 

int main() 
{ 
	
	int V = 5;  
	int E = 8; 
	struct Graph* graph = createGraph(V, E); 


	graph->edge[0].src = 0; 
	graph->edge[0].dest = 1; 
	graph->edge[0].weight = -1; 

	
	graph->edge[1].src = 0; 
	graph->edge[1].dest = 2; 
	graph->edge[1].weight = 4; 

	
	graph->edge[2].src = 1; 
	graph->edge[2].dest = 2; 
	graph->edge[2].weight = 3; 

	graph->edge[3].src = 1; 
	graph->edge[3].dest = 3; 
	graph->edge[3].weight = 2; 

	
	graph->edge[4].src = 1; 
	graph->edge[4].dest = 4; 
	graph->edge[4].weight = 2; 

	graph->edge[5].src = 3; 
	graph->edge[5].dest = 2; 
	graph->edge[5].weight = 5; 

	graph->edge[6].src = 3; 
	graph->edge[6].dest = 1; 
	graph->edge[6].weight = 1; 

	graph->edge[7].src = 4; 
	graph->edge[7].dest = 3; 
	graph->edge[7].weight = -3; 

	BellmanFord(graph, 0); 

	return 0; 
}