Wiki OI 1080 线段树练习

题目链接：http://wikioi.com/problem/1080/

算法与思路：树状数组，虽然这题题目是线段树练习，但是明显有单点更新，区间求和的特征，

所以树状数组也能做，至于思路就不赘述了，不懂树状数组可以看我前面几篇相关的题解。

#include<stdio.h>
#include<string.h>
int n, m;
int a[100010];
int lowbit(int x)
{
	return x & (-x);
} 
void update(int pos, int num)
{
	while(pos <= n)
	{
		a[pos] += num;
		pos += lowbit(pos);
	}
}
int sum(int x)
{
	int sum = 0;
	while(x > 0)
	{
		sum += a[x];
		x -= lowbit(x);
	}
	return sum;
}
int main()
{
	int i, j, temp;
	int que, x, y;
	scanf("%d", &n);
	memset(a, 0, sizeof(a));
	for(i = 1; i <= n; i++)
	{
		scanf("%d", &temp);
		update(i, temp);
	} 
	scanf("%d", &m);
	for(i = 1; i <= m; i++)
	{
		scanf("%d %d %d", &que, &x, & y);
		if(que == 1)
			update(x, y);
		else
		    printf("%d\n", sum(y) - sum(x - 1));
	}
	return 0;
}