Cod sursa(job #144253)

Utilizator astronomyAirinei Adrian astronomy Data 27 februarie 2008 13:28:08
Problema Sortare topologica Scor Ascuns
Compilator cpp Status done
Runda Marime 1.13 kb
#include <cstdio>
#include <cstring>
#include <vector>
using namespace std;

#define MAXN 50100
#define pb push_back

int N, M, deg[MAXN], Q[MAXN]; vector<int> G[MAXN];

// deg[x] = gradul exterior al nodului x
// folosesc o coada Q in care introduc pe rand nodurile care
// au gradul exterior zero
// complexitate O(N+M)

void solve(void)
{
    int i, x; vector<int>::iterator it;
    
    for(x = 1; x <= N; x++)
     if(deg[x] == 0) Q[++Q[0]] = x;

    for(i = 1; i <= N; i++)
    {
        x = Q[i];
        for(it = G[x].begin(); it != G[x].end(); ++it)
        {
            deg[*it]--;
            if(deg[*it] == 0) Q[++Q[0]] = *it;
        }
    }
}

void read_data(void)
{
    int i, a, b;

    scanf("%d %d\n", &N, &M);
    for(i = 1; i <= M; i++)
        scanf("%d %d\n", &a, &b), G[a].pb(b), deg[b]++;
}

void write_data(void)
{
    int i;

    for(i = 1; i <= N; i++)
        printf("%d ", Q[i]);
}

int main(void)
{
    freopen("sortaret.in", "rt", stdin);
    freopen("sortaret.out", "wt", stdout);

    read_data();
    solve();
    write_data();

    return 0;
}