Cod sursa(job #1443599)

Utilizator DanielRusuDaniel Rusu DanielRusu Data 28 mai 2015 12:34:54
Problema BFS - Parcurgere in latime Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.98 kb
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

ifstream fin("bfs.in");
ofstream fout("bfs.out");

int N, M, K;

vector < vector <int> > Graf;
vector <int> Dist;
queue <int> Q;

void BFS(int nod);

int main() {
    fin >> N >> M >> K;

    int x, y;

    Graf.resize(N + 1);
    Dist.resize(N + 1);

    for(int i = 1; i <= M; ++i) {
        fin >> x >> y;
        Graf[x].push_back(y);
    }

    BFS(K);

    for(int i = 1; i <= N; ++i) {
        if(i == K) fout << 0 << ' ';
        else {
            fout << (Dist[i] > 0 ? Dist[i] : -1) << ' ';
        }
    }

    fout << '\n';

    fin.close();
    fout.close();

    return 0;
}

void BFS(int nod) {
    Q.push(nod);

    while(!Q.empty()) {
        nod = Q.front();
        Q.pop();

        for(auto x : Graf[nod]) {
            if(!Dist[x] && x != K) {
                Dist[x] = Dist[nod] + 1;
                Q.push(x);
            }
        }
    }
}