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  • 树状数组

    彻底入门

    模板如下:

    int lowb(int t)
    {
        return t & (-t);
    }
    
    void add(int i,int v)
    {
        for( ;i < n;ar[i] += v,i += lowb(i));
        return ;
    }
    
    int sum(int i)
    {
        int s = 0;
        for(;i > 0;s += ar[i],i -= lowb(i));
        return s;
    }

    例题:ACM-ICPC 2018 徐州赛区网络预赛  H Ryuji doesn't want to study

    Ryuji is not a good student, and he doesn't want to study. But there are n books he should learn, each book has its knowledge a[i]a[i]a[i].

    Unfortunately, the longer he learns, the fewer he gets.

    That means, if he reads books from lll to rrr, he will get a[l]×L+a[l+1]×(L−1)+⋯+a[r−1]×2+a[r]a[l] imes L + a[l+1] imes (L-1) + cdots + a[r-1] imes 2 + a[r]a[l]×L+a[l+1]×(L−1)+⋯+a[r−1]×2+a[r] (LLL is the length of [ lll, rrr ] that equals to r−l+1r - l + 1r−l+1).

    Now Ryuji has qqq questions, you should answer him:

    111. If the question type is 111, you should answer how much knowledge he will get after he reads books [ lll, rrr ].

    222. If the question type is 222, Ryuji will change the ith book's knowledge to a new value.

    Input

    First line contains two integers nnn and qqq (nnn, q≤100000q le 100000q≤100000).

    The next line contains n integers represent a[i](a[i]≤1e9)a[i]( a[i] le 1e9)a[i](a[i]≤1e9) .

    Then in next qqq line each line contains three integers aaa, bbb, ccc, if a=1a = 1a=1, it means question type is 111, and bbb, ccc represents [ lll , rrr ]. if a=2a = 2a=2 , it means question type is 222 , and bbb, ccc means Ryuji changes the bth book' knowledge to ccc

    Output

    For each question, output one line with one integer represent the answer.

    样例输入

    5 3
    1 2 3 4 5
    1 1 3
    2 5 0
    1 4 5

    样例输出

    10
    8
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  • 原文地址:https://www.cnblogs.com/lu1nacy/p/10016632.html
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