Cod sursa(job #1364212)

Utilizator mirceadinoMircea Popoveniuc mirceadino Data 27 februarie 2015 15:47:07
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.48 kb
#include<cstdio>
#include<string>
#include<deque>
#include<bitset>
#include<vector>

using namespace std;

#ifdef HOME
const string inputFile = "input.txt";
const string outputFile = "output.txt";
#else
const string problemName = "bellmanford";
const string inputFile = problemName + ".in";
const string outputFile = problemName + ".out";
#endif

typedef pair<int, int> PII;
const int INF = (1 << 30);
const int NMAX = 50000 + 5;

int N, M;
vector<PII> V[NMAX];
int D[NMAX];
int nr[NMAX];
bitset<NMAX> viz;
deque<int> Q;

int bfs(int x) {
    int i, y, z;

    for(i = 1; i <= N; i++)
        D[i] = INF;

    D[x] = 0;
    Q.push_back(x);
    viz[x] = 1;

    while(!Q.empty()) {
        x = Q.front();
        Q.pop_front();

        viz[x] = 0;
        nr[x]++;

        if(nr[x] >= N)
            return 0;

        for(auto p : V[x]) {
            y = p.first;
            z = p.second;

            if(D[x] + z < D[y]) {
                D[y] = D[x] + z;
                if(!viz[y]) {
                    Q.push_back(y);
                    viz[y] = 1;
                }
            }
        }
    }

    return 1;
}

int main() {
    int i, x, y, z;

    freopen(inputFile.c_str(), "r", stdin);
    freopen(outputFile.c_str(), "w", stdout);

    scanf("%d%d", &N, &M);

    while(M--) {
        scanf("%d%d%d", &x, &y, &z);
        V[x].push_back(make_pair(y, z));
    }

    if(bfs(1))
        for(i = 2; i <= N; i++)
            printf("%d ", D[i]);
    else
        printf("Ciclu negativ!");

    return 0;
}