一道图论小题目

 1 #include <fstream>
 2 #include <iostream>
 3 #include <algorithm>
 4 #include <cstdio>
 5 #include <cstring>
 6 #include <cmath>
 7 #include <cstdlib>
 8 
 9 using namespace std;
10 
11 #define PI acos(-1.0)
12 #define EPS 1e-10
13 #define lll __int64
14 #define ll long long
15 #define INF 0x7fffffff
16 
17 const int N=10005;
18 int du[N];
19 
20 int main(){
21     //freopen("D:\\input.in","r",stdin);
22     //freopen("D:\\output.out","w",stdout);
23     int n,m,t1,t2;
24     scanf("%d %d",&n,&m);
25     for(int i=0;i<m;i++){
26         scanf("%d %d",&t1,&t2);
27         du[t1]++,du[t2]++;
28     }
29     ll ans=0;
30     for(int i=1;i<=n;i++)   ans+=(ll)du[i]*du[i];
31     printf("%lld\n",ans);
32     return 0;
33 }