ACDream 1213 Matrix Multiplication (01矩阵处理)

#pragma comprint(linker, "/STACK:1024000000,1024000000")
#include<cstdio>
#include<string>
#include<iostream>
#include<cstring>
#include<cmath>
#include<stack>
#include<queue>
#include<vector>
#include<map>
#include<stdlib.h>
#include<time.h>
#include<algorithm>
#define LL __int64
#define FIN freopen("in.txt","r",stdin)
using namespace std;
const int MAXN=10000+5;
int cnt[MAXN];
struct node
{
    int x,y;
}edge[100000+5];
int main()
{
    int n,m;
    while(scanf("%d %d",&n,&m)!=EOF)
    {
        memset(cnt,0,sizeof(cnt));
        for(int i=0;i<m;i++)
        {
            int u,v;
            scanf("%d %d",&u,&v);
            cnt[u]++;
            cnt[v]++;
            edge[i].x=u;
            edge[i].y=v;
        }
        long long ans=0;
        for(int i=0;i<m;i++)
        {
            int u=edge[i].x;
            int v=edge[i].y;
            ans+=cnt[u];
            ans+=cnt[v];
        }
        printf("%lld\n",ans);
    }
    return 0;
}