# c++ code for bellman ford algorithm code example

## Example: bellman ford code in c++

#include<iostream>
#define MAX 10
using namespace std;
typedef struct edge
{
int src;
int dest;
int wt;
}edge;
void bellman_ford(int nv,edge e[],int src_graph,int ne)
{
int u,v,weight,i,j=0;
int dis[MAX];

/* initializing array 'dis' with 999. 999 denotes infinite distance */
for(i=0;i<nv;i++)
{
dis[i]=999;
}

/* distance of source vertex from source vertex is o */
dis[src_graph]=0;

/* relaxing all the edges nv - 1 times */
for(i=0;i<nv-1;i++)
{
for(j=0;j<ne;j++)
{
u=e[j].src;
v=e[j].dest;
weight=e[j].wt;

if(dis[u]!=999 && dis[u]+weight < dis[v])
{
dis[v]=dis[u]+weight;
}
}

}

/* checking if negative cycle is present */
for(j=0;j<ne;j++)
{
u=e[j].src;
v=e[j].dest;
weight=e[j].wt;

if(dis[u]+weight < dis[v])
{
cout<<"\n\nNEGATIVE CYCLE PRESENT..!!\n";
return;
}
}

cout<<"\nVertex"<<"  Distance from source";
for(i=1;i<=nv;i++)
{
cout<<"\n"<<i<<"\t"<<dis[i];
}
}
int main()
{
int nv,ne,src_graph;
edge e[MAX];

cout<<"Enter the number of vertices: ";
cin>>nv;

/* if you enter no of vertices: 5 then vertices will be 1,2,3,4,5. so while giving input enter source and destination vertex accordingly */
printf("Enter the source vertex of the graph: ");
cin>>src_graph;

cout<<"\nEnter no. of edges: ";
cin>>ne;

for(int i=0;i<ne;i++)
{
cout<<"\nFor edge "<<i+1<<"=>";
cout<<"\nEnter source vertex :";
cin>>e[i].src;
cout<<"Enter destination vertex :";
cin>>e[i].dest;
cout<<"Enter weight :";
cin>>e[i].wt;
}

bellman_ford(nv,e,src_graph,ne);

return 0;
}