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Cod sursa(job #966783)
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
using namespace std;
int N, M, S;
ofstream out ("bfs.out");
struct Node
{
int data;
vector<Node*> adj;
};
vector<Node*> graph;
vector<int> steps;
void load ()
{
ifstream in ("bfs.in");
in >> N >> M >> S;
for (int i = 0; i < N; i++)
{
Node *n;
n = new Node;
n->data = i + 1;
graph.push_back(n);
steps.push_back(-1);
}
for (int i = 0; i < M; i++)
{
int a, b;
in >> a >> b;
graph[a-1]->adj.push_back(graph[b-1]);
}
in.close();
}
void bfs (int start)
{
queue<Node*> q;
q.push(graph[start-1]);
steps[start-1] = 0;
while (!q.empty())
{
Node *n = q.front();
q.pop();
for (int i = 0; i < n->adj.size(); i++)
{
if (steps[n->adj[i]->data - 1] == -1)
{
steps[n->adj[i]->data - 1] = steps[n->data - 1] + 1;
q.push (n->adj[i]);
}
}
}
}
void output ()
{
for (int i = 0; i < N; i++)
out << steps[i] << ' ';
out << endl;
out.close();
}
int main ()
{
load ();
bfs (S);
output();
return 0;
}