ACdream 1213 Matrix Multiplication【水题 、 找规律】

#include <cmath>
#include <queue>
#include <vector>
#include <cstdio>
#include <string>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <algorithm>
using namespace std;
//#pragma comment(linker, "/STACK:1024000000,1024000000")
#define FIN             freopen("input.txt","r",stdin)
#define FOUT            freopen("output.txt","w",stdout)
#define CASE(T)         for(scanf("%d",&T);T--;)
typedef long long LL;
const int maxn = 10000 + 5;
int N, M, cnt[maxn];
int main()
{
//    FIN;
    int a, b;
    while(~scanf("%d %d", &N, &M))
    {
        memset(cnt, 0, sizeof(cnt));
        for(int i = 1; i <= M; i++)
        {
            scanf("%d %d", &a, &b);
            cnt[a]++, cnt[b]++;
        }
        LL ans = 0;
        for(int i = 1; i <= N; i++)
        {
            ans += (LL)(cnt[i] * (cnt[i] - 1) / 2);
        }
        ans *= 2;
        ans += 2 * M;
        printf("%lld\n", ans);
    }
    return 0;
}

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