树状数组模板

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 //https://www.cnblogs.com/hsd-/p/6139376.html
 4 int a[MAXN],tree[MAXN];
 5 //低位一
 6 int lowbit(int t)
 7 {
 8     return t&(-t);
 9 }
10 
11 //区间更新
12 void update(int x,int y)
13 {
14     while(x<=maxn)
15     {
16         tree[x]+=y;
17         x+=lowbit(x);
18     }
19 
20 }
21 
22 //区间查询
23 int getsum(int x)
24 {
25     int ans=0;
26     while(x>=1)
27     {
28         ans+=tree[x];
29         x-=lowbit(x);
30     }
31     return ans;
32 }
33 //更新和查询的为前缀和