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  • codeforces 86D D. Powerful array(莫队算法)

    题目链接:

    D. Powerful array

    time limit per test
    5 seconds
    memory limit per test
    256 megabytes
    input
    standard input
    output
    standard output

    An array of positive integers a1, a2, ..., an is given. Let us consider its arbitrary subarray al, al + 1..., ar, where 1 ≤ l ≤ r ≤ n. For every positive integer s denote by Ks the number of occurrences of s into the subarray. We call the power of the subarray the sum of productsKs·Ks·s for every positive integer s. The sum contains only finite number of nonzero summands as the number of different values in the array is indeed finite.

    You should calculate the power of t given subarrays.

    Input

    First line contains two integers n and t (1 ≤ n, t ≤ 200000) — the array length and the number of queries correspondingly.

    Second line contains n positive integers ai (1 ≤ ai ≤ 106) — the elements of the array.

    Next t lines contain two positive integers lr (1 ≤ l ≤ r ≤ n) each — the indices of the left and the right ends of the corresponding subarray.

    Output

    Output t lines, the i-th line of the output should contain single positive integer — the power of the i-th query subarray.

    Please, do not use %lld specificator to read or write 64-bit integers in C++. It is preferred to use cout stream (also you may use%I64d).

    Examples
    input
    3 2
    1 2 1
    1 2
    1 3
    output
    3
    6
    input
    8 3
    1 1 2 2 1 3 1 1
    2 7
    1 6
    2 7
    output
    20
    20
    20
    Note

    Consider the following array (see the second sample) and its [2, 7] subarray (elements of the subarray are colored):

    Then K1 = 3, K2 = 2, K3 = 1, so the power is equal to 32·1 + 22·2 + 12·3 = 20.
    AC代码:
    #include <bits/stdc++.h>
    using namespace std;
    const int N=1e6+4;
    int n,t;
    long long a[N],num[N],ans[N];
    struct node
    {
       /* friend bool operator< ()
        {
    
        }*/
        int l,r,id,pos;
    };
    node qu[N];
    int cmp(node x,node y)
    {
        if(x.pos==y.pos)return x.r<y.r;
            return x.l<y.l;
    }
    void solve()
    {
        long long temp=0;
        int le=1,ri=0;
        for(int i=1;i<=t;i++)
        {
            while(ri<qu[i].r)
            {
                ri++;
                temp+=((num[a[ri]]<<1)+1)*a[ri];
                num[a[ri]]++;
            }
            while(ri>qu[i].r)
            {
                num[a[ri]]--;
                temp-=((num[a[ri]]<<1)+1)*a[ri];
                ri--;
            }
            while(le<qu[i].l)
            {
                num[a[le]]--;
                temp-=((num[a[le]]<<1)+1)*a[le];
                le++;
            }
            while(le>qu[i].l)
            {
                le--;
                temp+=((num[a[le]]<<1)+1)*a[le];
                num[a[le]]++;
            }
            ans[qu[i].id]=temp;
        }
    }
    
    int main()
    {
        scanf("%d%d",&n,&t);
        for(int i=1;i<=n;i++)
        {
            scanf("%I64d",&a[i]);
        }
        int sq=sqrt(n);
        for(int i=1;i<=t;i++)
        {
            scanf("%d%d",&qu[i].l,&qu[i].r);
            qu[i].id=i;
            qu[i].pos=qu[i].l/sq;
        }
        sort(qu+1,qu+t+1,cmp);
        solve();
        for(int i=1;i<=t;i++)
        {
            printf("%I64d
    ",ans[i]);
        }
        return 0;
    }
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  • 原文地址:https://www.cnblogs.com/zhangchengc919/p/5309305.html
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