题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=1285
#include<bits/stdc++.h>
using namespace std;
const int maxn = 515;
int mp[maxn][maxn];
int _in[maxn];
int ans[maxn];
int N, M;
void init()
{
memset(_in, 0, sizeof(_in));
memset(ans, 0, sizeof(ans));
memset(mp, 0, sizeof(mp));
}
void toposort()
{
for (int i = 1; i <= N; i++)
{
for (int j = 1; j <= N; j++)
{
if(mp[i][j]) _in[j]++;
}
}
for (int i = 1; i <= N; i++){
int k = 1;
while(_in[k] != 0) k++;
ans[i] = k;
_in[k] = -1;
for (int j = 1; j <= N; j++){
if(mp[k][j]) _in[j]--;
}
}
}
int main()
{
while(~scanf("%d%d", &N, &M)){
init();
for (int i = 0; i < M; i++){
int a, b;
scanf("%d%d", &a, &b);
mp[a][b] = 1;
}
toposort();
for (int i = 1; i < N; i++){
printf("%d ", ans[i]);
}
printf("%d\n", ans[N]);
}
return 0;
}