拓扑排序-

#include <iostream>

#include <stdio.h>

#include <memory.h>

#include <vector>

using namespace std;

 

const int N = 505;

 

int degree[N], res[N];

bool map[N][N];

vector<int> a[N];

int n, m;

 

void Topo()

{

    int i, j, p;

    for(i = 1; i <= n; i++)

    {

        p = -1;

        for(j = 1; j <= n; j++)

        {

            if(degree[j] == 0)

            {

                degree[j]--;

                res[i] = p = j;

                break;

            }

        }

        for(j = 1; j <= n; j++)

        {

            if(map[p][j] == true)

            {

                map[p][j] = false;

                degree[j]--;

            }

        }

    }

}

 

void output()

{

    int i;

    printf("%d", res[1]);

    for(i = 2; i <= n; i++)

    {

        printf(" %d", res[i]);

    }

    printf("\n");

}

 

int main()

{

    int i, x, y;

    while(scanf("%d %d", &n, &m) != EOF)

    {

        memset(map, false, sizeof(map));

        memset(degree, 0, sizeof(degree));

        memset(res, 0, sizeof(res));

        for(i = 1; i <= n; i++) a[i].clear();

        for(i = 1; i <= m; i++)

        {

            scanf("%d %d", &x, &y);

            if(map[x][y] == false)

            {

                map[x][y] = true;

                degree[y]++;

            }

        }

        Topo();

        output();

    }

 

    return 0;

}