樹狀陣列

程式碼如下：

#include <iostream>
#include <cstdio>

using namespace std;

const int N = 500005;

int a[N],c[N],n,m,k,x,y;

int lowbit(int i)
{
	return i & (-i);
}

int add(int loc,int value)
{
	for(int i = loc; i <= n; i += lowbit(i))
		c[i] += value;
	return 0;
}

int query(int loc)
{
	int
 
 sum =  0;
	for(int i = loc; i > 0; i -= lowbit(i))
		sum += c[i];
	return sum ;
}

int main()
{
	scanf("%d%d",&n,&m);
	for(int i = 1; i <= n; i ++)
		scanf("%d",&a[i]);
	for(int i = 1; i <= n; i ++)
		for(int j = i-lowbit(i)+1;j <= i; j ++)
			c[i] += a[j];
	while(m --)
	{
		scanf
 
("%d%d%d",&k,&x,&y);
		if(k == 1)
		{
			add(x,y);
		}
		if(k == 2)
		{
			int ans = query(y) - query(x-1);
			printf("%d\n",ans);
		}
	}
	return 0;
}