Cod sursa(job #3251426)

Utilizator IleaIlea Bogdan Ilea Data 26 octombrie 2024 00:08:49
Problema Algoritmul Bellman-Ford Scor 20
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.32 kb
#include <bits/stdc++.h>

using namespace std;

string file="bellmanford";
ifstream fin(file+".in");
ofstream fout(file+".out");

map<int, map<int, int> > g;
vector<bool> viz;
vector<int> b;
void bellmanFord(int i)
{
    queue<int> q;
    q.push(i);
    while (!q.empty()){
        i=q.front();
        q.pop();
        for (auto it:g[i]){
            if (!viz[it.first] || b[it.first]>b[i]+it.second){
                b[it.first]=b[i]+it.second;
                q.push(it.first);
                viz[it.first]=1;
            }
        }
    }
}
int glob_i;
void cic(int i, int nr)
{
    //cout<<i<<endl;
    if (i==glob_i && nr<0){
        fout<<"Ciclu negativ!";
        exit(0);
    }
    for (auto it:g[i]){
        if (!viz[it.first]){
            viz[it.first]=1;
            cic(it.first, nr+it.second);
            viz[it.first]=0;
        }
    }
}
void solve(int n)
{
    for (int i=1; i<=n; i++){
        glob_i=i;
        cic(i, 0);
    }
}
int main()
{
    int n, m;
    fin>>n>>m;
    for (int i=0; i<m; i++){
        int x, y, z;
        fin>>x>>y>>z;
        g[x][y]=z;
    }
    b.resize(n+1), viz.resize(n+1);
    solve(n);
    viz.clear(), viz.resize(n+1);
    viz[1]=1;
    bellmanFord(1);
    for (int i=2; i<=n; i++){
        fout<<b[i]<<" ";
    }
    return 0;
}