對於同樣的單點更新和區間求和功能，樹狀陣列空間上優於線段樹，且程式碼更簡便。

#include<cstdio>
#include<cstring>

using namespace std;

int N,c[50005];

int lowbit (int i){
	return i&(-i);
}
//讓點i值加value 
void add(int i,int value){ 
	while(i<=N){
		c[i]+=value;
		i+=lowbit(i);
	}
}
//求區間[1,i]的和 
int sum(int i){
	int sum=0;
	while(i>0){
		sum+=c[i];
		i-=lowbit(i);
	}
	return sum;
}

int main(){
	int t,cas=0,d;
	scanf("%d",&t);
	while(t--){
		printf("Case %d:\n",++cas);
		scanf("%d",&N);
		memset(c,0,sizeof(c));
		for(int i=1;i<=N;i++){
			scanf("%d",&d);
			add(i,d);
		}
		char command[15];
		int x,y;
		while(~scanf("%s",command)&&command[0]!='E'){
			scanf("%d%d",&x,&y);
			if(command[0]=='Q') printf("%d\n",sum(y)-sum(x-1));
			else if(command[0]=='A') add(x,y);
			else add(x,-y);
		}
	}
	return 0;
}