寒假集训之树状数组

#include <bits/stdc++.h>
using namespace std;
const int maxn=1000000;
int tree[maxn+10];
int a[maxn+10];
int n;
inline int lowbit(int x)
{
return (x&-x);
}
void add(int x,int value)
{
for(int i=x;i<=n;i+=lowbit(i))
tree[i]+=value;
}
long long get(int x)
{
long long sum=0;
for(int i=x;i;i-=lowbit(i))
sum+=tree[i];
return sum;
}
int main()
{
int t;cin>>t;
int tmp=t;
while(t--)
{
printf("Case %d:\n",tmp-t);
scanf("%d",&n);
memset(tree,0,sizeof tree);
for(int i=1;i<=n;i++)
{
scanf("%d",&a[i]);
add(i,a[i]);
}
char s[10];
int i,j;
while(scanf("%s",s)&&strcmp(s,"End")!=0)
{
scanf("%d%d",&i,&j);
if(strcmp(s,"Query")==0)
printf("%lld\n",get(j)-get(i-1));//查询区间之和用减法就好
else if(strcmp(s,"Add")==0)
add(i,j);
else if(strcmp(s,"Sub")==0)
add(i,-1*j);//某个点减少了，用加负数
}
}
return 0;
}