Cod sursa(job #860710)

Utilizator cernat.catallinFMI Cernat Catalin Stefan cernat.catallin Data 20 ianuarie 2013 18:02:55
Problema BFS - Parcurgere in latime Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.17 kb
#include <fstream>
#include <iostream>
#include <vector>
#include <queue>
using namespace std;

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

vector < vector <unsigned int> > graf;
vector <bool> visitat;
vector <int> drum;
int n, m, s;

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

void afisare(){
    for(int i = 1; i <= n; ++i){
        if(drum[i] == 0 && i != s) g << -1 << " ";
        else g << drum[i] << " ";
    }
    g.close();
}

void bfs(){
    queue<unsigned int> coada;
    vector<unsigned int>::iterator it;
    visitat.resize(n+1);
    drum.resize(n+1, 0);
    visitat[s] = 1;
    coada.push(s);

    while(!coada.empty()){
        for(it = graf[coada.front()].begin(); it != graf[coada.front()].end(); ++it ){
            if(!visitat[*it]){
                visitat[*it] = 1;
                drum[*it] = drum[coada.front()] + 1;
                coada.push(*it);
            }
        }
        coada.pop();
    }
}

int main(){
    citire();
    bfs();
    afisare();

    return 0;
}