Cod sursa(job #1550724)

Utilizator fromzerotoheroFROM ZERO fromzerotohero Data 14 decembrie 2015 16:43:08
Problema BFS - Parcurgere in latime Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.22 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>

#define nmax 100001
#define inf (1<<30)

using namespace std;

int n, m, s;
int x, y;
vector <int> G[nmax];

int cost[nmax];
queue < pair<int, int> > q;

void bfs(int x)
{
    q.push(make_pair(x, cost[x]));
    
    while (!q.empty())
    {
        int nod = q.front().first;
        int costNod = q.front().second;
        
        q.pop();
        
        for (int i = 0; i < G[nod].size(); i++)
        {
            int vecin = G[nod][i];
            
            if (costNod + 1 < cost[vecin])
            {
                cost[vecin] = costNod + 1;
                q.push(make_pair(vecin, cost[vecin]));
            
            }
            
        }
        
    }
    
}

int main()
{
    
    ifstream fi("bfs.in");
    ofstream fo("bfs.out");
    
    fi >> n >> m >> s;
    for (int i = 1; i <= m; i++)
        fi >> x >> y,
        G[x].push_back(y);
    
    for (int i = 1; i <= n; i++)
        cost[i] = inf;
    cost[s] = 0;
    
    bfs(s);
    
    for (int i = 1; i <= n; i++)
    {
        if (cost[i] == inf)
            cost[i] = -1;
        
        fo << cost[i] << " ";
        
    }
    
    fi.close();
    fo.close();
    
    return 0;

}