拓扑排序 ： hdu 1285 示例

#include <iostream>
#include <string>
#include <cstring>
#include <cstdlib>
#include <cstdio>
#include <cmath>
#include <vector>
#include <stack>
#include <deque>
#include <queue>
#include <bitset>
#include <list>
#include <map>
#include <set>
#include <iterator>
#include <algorithm>
#include <functional>
#include <utility>
#include <sstream>
#include <climits>
#include <cassert>
#define BUG puts("here!!!");

using namespace std;

const int N = 505;
int edge

;
int degree
;
int vis
;
int n, m;
int main() {
while(cin >> n >> m) {
memset(edge, 0, sizeof(edge));
memset(degree, 0, sizeof(degree));
int a, b;
while(m--) {
cin >> a >> b;
if(edge[a][b]) continue;
edge[a][b] = 1;
degree[b]++;
}
int k = 0;
memset(vis, 0, sizeof(vis));
int temp;
for(int i = 1; i <= n; i++) {
for(int j = 1; j <= n; j++) {
if(degree[j] == 0 && !vis[j]) {
cout << j;
k++;
vis[j] = 1;
temp = j;
break;
}
}
for(int j = 1; j <= n; j++) {
if(edge[temp][j] == 1) {
degree[j]--;
}
}
if(k != n) cout << ' ';
else {
cout << endl;
break;
}
}
}
return 0;
}