Bellman-Ford

#include <bits/stdc++.h>
using namespace std;
#define MAX 100
typedef long long int ll;
vector< vector<ll> > graph;
ll dist[MAX+1];
ll parent[MAX+1];
ll n, m;
void InitializeSingleSource(ll s)
{
    for(ll i = 1; i <= n; i++)
    {
        dist[i] = INT_MAX;
        parent[i] = 0;
    }
    dist[s] = 0;
}
void Relax(ll u, ll v, ll w)
{
    if(dist[v] > dist[u]+w)
    {
        dist[v] = dist[u]+w;
        parent[v] = u;
    }
}
bool BellmanFord(ll s)
{
    InitializeSingleSource(s);
    for(ll i = 1; i < n; i++)
    {
        for(ll j = 0; j < m; j++)
        {
            ll u = graph[j][0], v = graph[j][1], w =graph[j][2];
            Relax(u,v,w);
        }
    }
    for(ll i = 0; i < m; i++)
    {
        ll u = graph[i][0], v = graph[i][1], w = graph[i][2];
        if(dist[v] > dist[u]+w)
        {
            return false;
        }
    }
    return true;
}

int main()
{
    ll s = 4;
    cin >> n >> m;
    for(ll i = 0; i < m; i++)
    {
        ll u, v, w;
        vector<ll> V;
        cin >> u >> v >> w;
        V.push_back(u);
        V.push_back(v);
        V.push_back(w);
        graph.push_back(V);
    }
    if(BellmanFord(s))
    {
        for(ll i = 1; i <= n; i++)
        {
            if(dist[i] == INT_MAX)
            {
                cout << "There is not route from " << s << " to " << i << endl;
            }
            else
            {
                cout << "Min distance from " << s << " to ";
                cout << i << " is " << dist[i] << endl;
            }
        }
        cout << endl;
    }
    else
    {
        cout << "Graph contains negative cycle" << endl;
    }
    return 0;
}