Cod sursa(job #786539)

Utilizator cernat.catallinFMI Cernat Catalin Stefan cernat.catallin Data 11 septembrie 2012 16:17:39
Problema BFS - Parcurgere in latime Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.12 kb
#include <fstream>
#include <iostream>
#include <vector>
#include <queue>
using namespace std;

vector< vector<unsigned int> > Graph;
vector<int> Cost;
int n, m, s;

ofstream g ("bfs.out");

void Read(){
    ifstream f ("bfs.in");
    f >> n >> m >> s;
    Graph.resize(n+1);
    for(int i = 1; i <= m; ++i){
        int x, y;
        f >> x >> y;
        Graph[x].push_back(y);
    }
    for(int i = 1; i <= n; ++i){
        vector<unsigned int>(Graph[i]).swap(Graph[i]);
    }
    f.close();
}

void Bfs(){
    queue<unsigned int> Que;
    Cost.resize(n+1, -1);
    Que.push(s);
    Cost[s] = 0;
    vector<unsigned int>::iterator it;
    while(!Que.empty()){
        for(it = Graph[Que.front()].begin(); it != Graph[Que.front()].end(); ++it){
            if(Cost[*it] == -1){
                Que.push(*it);
                Cost[*it] = Cost[Que.front()]+1;
            }
        }
        Que.pop();
    }
}

void Write(){
    for(int i = 1; i <= n; ++i){
        g << Cost[i] << " ";
    }
    g << "\n";
    g.close();
}

int main(){
    Read();
    Bfs();
    Write();
    return 0;
}