【模板】拓扑排序

【模板】拓扑排序

#include<iostream>
#include<cstring>
#include<cstdio>
#include<string>
#include<queue>
#include<stack>
#include<algorithm>
#include<vector>
#include<map>
using namespace std;
const int INF= 0x3f3f3f3f;
int head[500001];
int ans=0;
struct Edge
{
    int u, v, w, next;
}e[500001];
void add(int u,int v)
{
    e[++ans].next = head[u];
    e[ans].v = v;
    head[u] = ans;
}
int IN[500001];//入度
int OUT[500001];//出度
int d[500001];
int n, m;
void topsort()//拓扑排序
{
    queue<int> q;
    for (int i = 1; i <= n; i++)
    {
       if(IN[i]==0)//入读为0的点入队列
       {
           q.push(i);
           d[i] = 1;
       }
    }
    while(!q.empty())
     {
         int t = q.front();
         q.pop();
         for (int i = head[t]; i != 0;i=e[i].next)
         {
             int uu = e[i].v;
             d[uu] = (d[t]+d[uu])%80112002;
             IN[uu]--;//入度--
             if(IN[uu]==0)//入读为0的点入队列
             {
                 q.push(uu);
             }
         }
     }

}
int main()
{
    cin >> n >> m;
     memset(IN, 0, sizeof(IN));
      memset(d, 0, sizeof(d));
     memset(OUT, 0, sizeof(OUT));
    for (int i = 1; i <= m;i++)
    {
        int x, y;
        cin >> x >> y;
        add(x, y);
        IN[y]++;
        OUT[x]++;
    }
    topsort();
    int total = 0;
    for (int i = 1; i <= n;i++)
    {
        if(OUT[i]==0)
        total= (total+d[i])%80112002;
    }
    cout << total%80112002;
    return 0;
}