Cod sursa(job #2196522)

Utilizator cristiancreteanuCristian Creteanu cristiancreteanu Data 19 aprilie 2018 17:26:49
Problema BFS - Parcurgere in latime Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.11 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

int main() {

    int x, y, N, M, S, node, i, size, level;
    ifstream f("bfs.in");
//    ifstream f("../input");
    ofstream g("bfs.out");

    f >> N >> M >> S;

    vector<vector<int>> adj(N + 1);
    for (i = 1; i <= M; ++i) {
        f >> x >> y;

        adj[x].push_back(y);
    }

    vector<int> visited(N + 1, -1);
    queue<int> bfs;

    bfs.push(S);
    visited[S] = 0;
    bfs.push(0);

    level = 0;
    while (!bfs.empty()) {
        node = bfs.front();
        bfs.pop();

        if (node == 0) {
            if (bfs.empty()) {
                break;
            }

            level++;
            bfs.push(0);
            continue;
        }

        size = adj[node].size();
        for (i = 0; i < size; ++i) {
            if (visited[adj[node][i]] == -1) {
                bfs.push(adj[node][i]);
                visited[adj[node][i]] = level + 1;
            }
        }
    }

    for(i = 1; i <= N; ++i) {
        g << visited[i] << ' ';
    }
    g << '\n';

    g.close();
    f.close();

    return 0;
}