lowbit 树状数组

总结一下：x&(-x)，当x为0时结果为0；x为奇数时，结果为1；x为偶数时，结果为x中2的最大次方的因子。.

 

 

    #include<bits/stdc++.h>
    #include<iostream>

    using namespace std;
    typedef long long ll;
    const int NS=1e6+5;
    int dir[4][2]={{1,0},{-1,0},{0,1},{0,-1}};
    ll mod=19260817;
    ll shuzu[NS*4];
    int a,b;
    int lowbit(int a)
    {
        return a&(-a);
    }
    void update(int x,int y)
    {
        while(x<=4*a)
        {
            shuzu[x]+=y;
            x+=lowbit(x);
        }
    }
    ll getsum(int x)
    {
        ll sum=0;
        while(x>0)
        {
            sum+=shuzu[x];
            x-=lowbit(x);
        }
        return sum;
    }
    int main()
    {

        ios::sync_with_stdio(false);
        cin.tie(0);
        cout.tie(0);

        cin>>a>>b;
        for(int i=1;i<=a;i++)
        {
            ll temp;
            cin>>temp;
            update(i,temp);
        }
        while(b--)
        {
            int x,y,z;
            cin>>x>>y>>z;
            if(x==1)
            {
                update(y,z);
            }
            else
            {
                cout<<getsum(z)-getsum(y-1)<<'\n';
            }
        }

    }