hdu 1285 拓扑排序

/*
题意：中文题

题解：拓扑排序
*/
#include <cstdio>
#include <cstring>

#define MAXN 505
int toposort(int n,int mat[][MAXN],int* ret){
    int d[MAXN],i,j,k;
    for (i=0;i<n;i++)
        for (d[i]=j=0;j<n;d[i]+=mat[j++][i]);
    for (k=0;k<n;ret[k++]=i){
        for (i=0;d[i]&&i<n;i++);
        if (i==n)
            return 0;
        for (d[i]=-1,j=0;j<n;j++)
            d[j]-=mat[i][j];
    }
    return 1;
}

int ans[MAXN];
int gra[MAXN][MAXN];

int main(void)
{
    int n,m;
    while (~scanf("%d%d",&n,&m))
    {
        memset(gra,0,sizeof(gra));
        while (m--)
        {
            int p1,p2;
            scanf("%d%d",&p1,&p2);
            p1--;
            p2--;
            gra[p1][p2] = 1;
        }
        toposort(n,gra,ans);
        printf("%d",ans[0]+1);
        for(int i=1; i<n; i++)
            printf(" %d",ans[i]+1);
        printf("\n");
    }
    return 0;
}