HDU 1166 敌兵布阵（线段树）

#include <stdio.h>
#define maxn 50005
int ans;
struct 
{
	int l, r, sum;
	int mid()
	{
		return (l + r)>>1;
	}
}node[maxn*4];
void buildtree(int left, int right, int u)
{
	node[u].l = left;
	node[u].r = right;
	if(left == right)
	{
		scanf("%d",&node[u].sum);
		return;
	}
	int mid = node[u].mid();
	buildtree(left, mid, u<<1);
	buildtree(mid+1, right, u<<1|1);
	node[u].sum = node[u<<1].sum + node[u<<1|1].sum;
}
void update(int b, int s, int left, int right, int u)
{
	if(left==right)
	{
		node[u].sum+=s;
		return;
	}
	int mid = node[u].mid();
	if(b<=mid) update(b, s, left, mid, u<<1);
	else if(b>mid) update(b, s, mid+1, right, u<<1|1);
	node[u].sum = node[u<<1].sum + node[u<<1|1].sum;
}
void query(int b, int s, int left, int right, int u)
{
	if(b<=left && right<=s)
	{
		ans+=node[u].sum;
		return;
	}
	int mid = node[u].mid();
	if(s<=mid) query(b, s, left, mid, u<<1);
	else if(mid<b) query(b, s, mid+1, right, u<<1|1);
	else
	{
		query(b, s, left, mid, u<<1);
		query(b, s, mid+1, right, u<<1|1);
	}
}
int main()
{
	int t;
	char str[10];
	scanf("%d",&t);
	int cas=1;
	while(t--)
	{
		int n;
		scanf("%d",&n);
		buildtree(1, n, 1);
		printf("Case %d:\n",cas++);
		getchar();
		while(scanf("%s",str)!=EOF)
		{
			int b,s;
			getchar();
			if(str[0]=='E') break;
			scanf("%d%d",&b,&s);
			if(str[0]=='A')
			{
				update(b, s, 1, n, 1);
			}
			else if(str[0]=='S')
			{
				update(b, -s, 1, n, 1);
			}
			else
			{
				ans=0;
				query(b, s, 1, n, 1);
				printf("%d\n",ans);
			}
		}
	}
	return 0;
}