CF86D

题解：

莫队分块

分块大小为sqrt(n)

代码：

#include<bits/stdc++.h>
using namespace std;
const int N=200005;
typedef long long ll;
ll a[N],cnt[N*5],ans[N],res;
int n,t,L,R;
struct node{int x,y,l,p;}q[N];
int cmp(const node &x,const node &y) 
{
    if (x.l==y.l)return x.y<y.y;
    return x.l<y.l;
}
void query(int x, int y, int flag) 
{
    if (flag)
     {
        for (int i=x;i<L;i++)
         {
            res+=((cnt[a[i]]<<1)+1)*a[i];
            cnt[a[i]]++;
         }
        for (int i=L;i<x;i++)
         {
            cnt[a[i]]--;
            res-=((cnt[a[i]]<<1)+1)*a[i];
         }
        for (int i=y+1;i<=R;i++)
         {
            cnt[a[i]]--;
            res-=((cnt[a[i]]<<1)+1)*a[i];
         }
        for (int i=R+1;i<=y;i++)
         {
            res+=((cnt[a[i]]<<1)+1)*a[i];
            cnt[a[i]]++;
         }
     }
    else
     for (int i=x;i<=y;i++)
      {
        res+=((cnt[a[i]]<<1)+1)*a[i];
        cnt[a[i]]++;
      }
    L=x;R=y;
}
int main() 
{
    scanf("%d%d",&n,&t);
    for (int i=1;i<=n;i++)scanf("%I64d", &a[i]);
    int block_size=sqrt(n);
    for (int i=0;i<t;i++)
     {
        scanf("%d%d",&q[i].x,&q[i].y);
        q[i].l=(q[i].x-1)/block_size;
        q[i].p=i;
     }
    sort(q,q+t,cmp);
    memset(cnt,0,sizeof(cnt));
    res=0;
    for (int i=0;i<t;i++)
     {
        query(q[i].x,q[i].y,i);
        ans[q[i].p]=res;
     }
    for (int i=0;i<t;i++)printf("%I64d\n",ans[i]);
    return 0;
}