树状数组区间修改单点查询模板

#include<cstdio>
#include<iostream>
using namespace std;
int a[100005],b[100005];
int lowbit(int x)
{
	return x&(-x);
}
int n;
void add(int x,int y)
{
	for(int i=x;i<=n;i+=lowbit(i))
	{
		b[i]+=y;
	}
}
int sum(int x)
{
	int ans=0;
	for(int i=x;i;i-=lowbit(i))
	{
		ans+=b[i];
	}
	return ans;
}
int main()
{
	freopen("shulieb.in","r",stdin);
	freopen("shulieb.out","w",stdout); 
	int m;
	scanf("%d",&n);
	for(int i=1;i<=n;i++)
	{
		scanf("%d",&a[i]);
		//add(i,a[i]);
	}
	scanf("%d",&m);
	int x,y,k;
	for(int i=1;i<=m;i++)
	{
		char s[10];
		scanf("%s",s);
		if(s[0]=='A')
		{
			scanf("%d%d%d",&x,&y,&k);
			add(x,k);
			add(y+1,-k);
		}
		else
		if(s[0]=='Q')
		{
			scanf("%d",&x);
			printf("%d\n",sum(x)+a[x]);
		}
	}
	return 0;
}