无前驱的顶点的拓扑排序

无前驱的顶点的拓扑排序算法，采用链式前向星存储图，队列实现拓扑排序

代码：

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
int i,j,w;
int head[100];
int indegree[100];
struct EdgeNode
{
    int to;
    int next;
};
EdgeNode Edge[1000];
int n,m;
int main()
{
    while(~scanf("%d%d",&n,&m))
    {
        memset(indegree,0,sizeof(indegree));
        memset(head,0,sizeof(head));
        for(int k = 1;k <= m;k ++)
        {
            cin >> i >> j;
            indegree[j] ++;
            Edge[k].to = j;
            Edge[k].next = head[i];
            head[i] = k;
        }
       
        for(int i = 1;i <= n;i ++)
        {
            for(int k = head[i];k != 0;k = Edge[k].next)
              cout << i << ' ' << j << endl;
        }
       
        int queue[100];
        int iq = 0;
        for(int i = 1;i <= n;i ++)
        {
            if(indegree[i] == 0)
               queue[iq ++] = i;
        }
        for(int i = 0;i < iq;i ++)
        {
            for(int k = head[queue[i]];k != 0;k = Edge[k].next)
            {
                indegree[Edge[k].to] --;
                if(indegree[Edge[k].to] == 0)
                   queue[iq ++] = Edge[k].to;
            }
        }
        for(int i = 0;i < iq;i ++)
           cout << queue[i] << ' ';
        cout << endl;
    }
}