[wikioi]奇怪的梦境

http://wikioi.com/problem/2833/

拓扑排序，居然1A，哈哈。

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <memory.h>
#define MAX(a, b) a>b?a:b
#define LEN 105
using namespace std;
 
int main()
{
    int n, m;
    scanf("%d%d", &n, &m);
    vector<vector<int> > graph(n+1);
    vector<int> indegree(n+1);
    vector<bool> visit(n+1);
    int ans = n;
    while (m--) {
        int x = 0;
        int y = 0;
        scanf("%d%d", &x, &y);
        indegree[y]++;
        graph[x].push_back(y);
    }
    queue<int> que;
    for (int i = 1; i <= n; i++) {
        if (indegree[i] == 0) {
            que.push(i);
            visit[i] = true;
            ans--;
        }
    }
    while (!que.empty()) {
        int node = que.front();
        que.pop();
        for (int i = 0; i < graph[node].size(); i++) {
            if (!visit[graph[node][i]]) {
                indegree[graph[node][i]]--;
                if (indegree[graph[node][i]] == 0) {
                    que.push(graph[node][i]);
                    visit[graph[node][i]] = true;
                    ans--;
                }
            }
        }
    }
    if (ans == 0) puts("o(∩_∩)o\n");
    else {
        puts("T_T\n");
        printf("%d\n", ans);
    }
    return 0;
}