Cod sursa(job #2376618)

Utilizator FlorinVladutCreta Florin FlorinVladut Data 8 martie 2019 16:46:54
Problema BFS - Parcurgere in latime Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.1 kb
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

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

int n, m, s;

const int Inf = 0x3f3f3f3f;
vector<vector<int>> G;
vector<int> d;
vector<bool> v;


void read()
{
    fin >> n >> m >> s;

    G = vector<vector<int>>(n + 1);
    d = vector<int>(n + 1, Inf);
    v = vector<bool>(n + 1);

    int a, b;

    while(fin >> a >> b)
    {
        G[a].push_back(b);
    }
}

void BFS(int x)
{
    queue<int> Q;
    Q.push(x);
    v[x] = true;
    d[x] = 0;

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

        for(auto& i : G[x])
        {
            if(!v[i])
            {
                Q.push(i);
                d[i] = d[x] + 1;
                v[i] = true;
            }
        }
    }

}

void write()
{
    for(int i = 1; i <= n; i++)
    {
        if(d[i] == Inf) fout << -1 << ' ';
        else
            fout << d[i] << ' ';
    }
}

int main()
{
    read();
    BFS(s);
    write();

    return 0;
}