HDU5695 拓扑排序

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
#include <queue>

using namespace std;
const int inf = 0x3f3f3f3f;
const int maxn = 100000 + 100;
int N, M;
vector<int> G[maxn];
int indegree[maxn];

int main() {
    int T;
    scanf("%d", &T);
    while(T--) {
        scanf("%d%d", &N, &M);
        for(int i=1; i<=N; i++) {
            indegree[i] = 0;
            G[i].clear();
        }
        for(int i=0; i<M; i++) {
            int u,  v;
            scanf("%d%d",  &u, &v);
            G[u].push_back(v);
            indegree[v]++;
        }
        priority_queue<int> que;
        for(int i=1; i<=N; i++) if(!indegree[i]) que.push(i);
        long long res = 0;
        int rk = inf;
        while(!que.empty()) {
            int num = que.top(); que.pop();
            rk = min(rk, num);
            res += rk;
            for(int i=0; i<G[num].size(); i++) {
                int v = G[num][i];
                indegree[v]--;
                if(!indegree[v]) que.push(v);
            }
        }
        printf("%lld\n", res);
    }
    return 0;
}