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Cod sursa(job #491211)
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
using namespace std;
#define infile "bfs.in"
#define outfile "bfs.out"
#define NMAX 100002
int m, n;
vector<int> adj[NMAX];
int arcs[NMAX];
void bfs(int source) {
queue<int> q;
for (int i = 1; i <= n; i++) arcs[i] = -1;
q.push(source);
arcs[source] = 0;
while (!q.empty()) {
int node = q.front();
q.pop();
vector<int>::iterator it = adj[node].begin();
for (; it != adj[node].end(); it++) {
if (arcs[*it] == -1) {
arcs[*it] = arcs[node] + 1;
q.push(*it);
} else if (arcs[*it] > arcs[node] + 1)
arcs[*it] = arcs[node] + 1;
}
}
}
int main() {
int s, a, b;
ifstream in(infile);
ofstream out(outfile);
in >> n >> m >> s;
for (int i = 0; i < m; i++) {
in >> a >> b;
adj[a].push_back(b);
}
bfs(s);
for (int i = 1; i <= n; i++)
out << arcs[i] << " ";
out << endl;
return 0;
}