【HDOJ】4857 逃生

很容易想到优先队列+拓扑排序。关键点是有限制条件者有限，无限制条件者在最后，条件相同者按序输出。因此采用逆序。

 #include <iostream>
 #include <queue>
 #include <algorithm>
 #include <cstdio>
 #include <cstring>
 using namespace std;

 #define MAXN 30005

 typedef struct {
     int to, next;
 } edge_st;

 edge_st edges[];
 int adj[MAXN], L;
 int deg[MAXN];
 int buf[MAXN];

 typedef struct node_st{
     int i;
     node_st() {}
     node_st(int ii) {
         i = ii;
     }
     friend bool operator <(node_st a, node_st b) {
         return a.i < b.i;
     }
 } node_st;

 void add(int u, int v) {
     edges[L].to = v;
     edges[L].next = adj[u];
     adj[u] = L++;
     ++deg[v];
 }

 void init() {
     L = ;
     memset(deg, , sizeof(deg));
     memset(adj, , sizeof(adj));
 }

 int main() {
     int T, n, m;
     int i, j, k;
     node_st nd;

     scanf("%d", &T);
     while (T--) {
         scanf("%d%d", &n, &m);
         init();
         while (m--) {
             scanf("%d %d", &j, &k);
             add(k, j);
         }
         priority_queue<node_st> Q;
         for (i=; i<=n; ++i)
             if (deg[i] == )
                 Q.push(node_st(i));
         k = ;
         while (!Q.empty()) {
             nd = Q.top();
             buf[k++] = nd.i;
             Q.pop();
             for (i=adj[nd.i]; i; i=edges[i].next) {
                 deg[edges[i].to]--;
                 if (deg[edges[i].to] == )
                     Q.push(node_st(edges[i].to));
             }
         }
         for (i=k-; i>=; --i)
             if (i)
                 printf("%d ", buf[i]);
             else
                 printf("%d\n", buf[i]);
     }

     return ;
 }