读懂题意就是水题，按照出现次数对下标排一下序，暴力。。

#include
     
      #include
      
       #include
       
        using namespace std;typedef long long ll;const int maxn = 1e4+77;ll cnt[maxn];ll r[maxn];bool cmp(int a,int b) { return cnt[a] > cnt[b]; }int main(){    int T;    scanf("%d",&T);    for(int k = 1; k <= T; k++){        int M,N,C;        scanf("%d%d%d",&M,&N,&C);        memset(cnt,0,sizeof(cnt));        for(int i = 0; i < M; i++){            int tmp;            scanf("%d",&tmp);            cnt[tmp]++;        }        for(int i = 0; i < N; i++) { r[i]  = i+1; }        sort(r,r+N,cmp);        ll amus = (r[0]*r[0])%C;        ll best = cnt[r[0]]*amus;        for(int i = 1; i < N; i++) {            amus += (r[i]*r[i])%C;            ll tmp = cnt[r[i]]*amus;            best = max(best,tmp);        }        printf("Case %d: %I64d\n",k,best);    }    return 0;}