Cod sursa(job #2176442)

Utilizator jeanFMI - Petcu Ion Cristian jean Data 17 martie 2018 13:50:23
Problema Algoritmul Bellman-Ford Scor 35
Compilator cpp Status done
Runda Arhiva educationala Marime 1.43 kb
#include<iostream>
#include<algorithm>
#include<vector>
#include<queue>
#define NMAX 50010
#define INF (1<<10)
using namespace std;

typedef pair<int, int> int_pair;

vector<int_pair> G[NMAX];
int dist[NMAX], cnt[NMAX];
bool in_queue[NMAX];


bool bellmanford(int start, int N) {
    queue<int> Q;
    Q.push(start);
    in_queue[start] = true;
    cnt[start] = 1;

    while (!Q.empty()) {
        int nod = Q.front();
        Q.pop();
        in_queue[nod] = false;

        for (auto &edge : G[nod]) {
            if (dist[edge.first] == INF || dist[edge.first] > dist[nod] + edge.second) {
                dist[edge.first] = dist[nod] + edge.second;       
                if (!in_queue[edge.first]) {
                    cnt[edge.first]++;
                    if (cnt[edge.first] == N) return false;
                    Q.push(edge.first);
                    in_queue[edge.first] = true;
                }
            }
        }
    } 

    return true;
}



int main() {
    freopen("bellmanford.in", "r", stdin);
    freopen("bellmanford.out", "w", stdout);
 
    int N, M, x, y, c, i;
    cin >> N >> M;
    for (i = 0; i < M; i++) {
        cin >> x >> y >> c;
        G[x].push_back(make_pair(y, c));
    }

    for (i = 2; i <= N; i++) {
        dist[i] = INF;
    }

    if (!bellmanford(1, N)) {
        cout << "Ciclu negativ!";
        return 0;
    }
    
    for (i = 2; i <= N; i++) {
        cout << dist[i] << ' ';
    }
 
    return 0;
}