[线段树][CODEVS 1080]题解

#include<cstdio>
#include<algorithm>
#include<cmath>
#include<iostream>
#define inf 0x3f3f3f3f
#define LL unsigned long long
#define lson u<<1,l,mid
#define rson u<<1|1,mid+1,r
#define maxn 200005
using namespace std;
struct node{
	int l,r;
	int s;
}e[4*maxn+1];
int n,m;
void build(int u,int l,int r)
{
	e[u].l=l;e[u].r=r;
	if(l==r)
	{
		scanf("%d",&e[u].s);
		return ;
	}
	int mid=(l+r)>>1;
	build(lson);
	build(rson);
	e[u].s=e[u<<1].s+e[u<<1|1].s;
	
}
void update(int u,int l,int r,int x,int add)
{
	if(l==r)
	{
		e[u].s+=add;
		return ;
	}
	int mid = (l+r)>>1;
	if(x<=mid)update(lson,x,add);
	else update(rson,x,add);
	e[u].s=e[u<<1].s+e[u<<1|1].s;
}
int query(int u,int l,int r,int x