Cod sursa(job #2191002)

Utilizator Narvik13Razvan Roatis Narvik13 Data 1 aprilie 2018 12:19:24
Problema BFS - Parcurgere in latime Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.94 kb
#include <fstream>
#include <vector>
#include <queue>
#define NMAX 100002
#define INF 0x3f3f3f3f

using namespace std;

ifstream f("bfs.in");
ofstream o("bfs.out");

int n,m,s,dist[NMAX];
vector <int> g[NMAX];
queue <int> q;

void input()
{
    f >> n >> m >> s;
    int x,y;
    for(int i = 1; i <= m; ++i)
    {
        f >> x >> y;
        g[x].push_back(y);
    }
}

void bfs()
{
    for(int i = 1; i <= n; ++i)
        dist[i] = INF;

    dist[s] = 0;
    q.push(s);

    int nod;
    while(not q.empty())
    {
        nod = q.front();
        q.pop();

        for(auto i: g[nod])
            if(dist[i] > dist[nod] + 1)
            {
                dist[i] = dist[nod] + 1;
                q.push(i);
            }
    }
}

void output()
{
    for(int i = 1; i <= n; ++i)
        o << (dist[i] == INF ? -1 : dist[i]) << ' ';
}

int main()
{
    input();
    bfs();
    output();
    return 0;
}