hdu 1166——敌兵布阵 （线段树）

基础线段树

#include<cstdio>
#include<iostream>
using namespace std;

struct Node
{
int l,r;
int sum;
int Mid(){return (l+r)/2;}
}tree[50010*4];

void build(int rt,int left,int right)
{
tree[rt].l=left;
tree[rt].r=right;
if(left!=right)
{
int mid=tree[rt].Mid();
build(rt*2,left,mid);
build(rt*2+1,mid+1,right);
tree[rt].sum=tree[2*rt].sum+tree[rt*2+1].sum;
}
else
scanf("%d",&tree[rt].sum);
}

void Add(int rt,int x,int y)
{
tree[rt].sum+=y;
if(tree[rt].l==tree[rt].r)
return ;
int mid=tree[rt].Mid();
if(x<=mid)
Add(rt*2,x,y);
else
Add(rt*2+1,x,y);
}

void Query(int &ans,int rt,int x,int y)
{
if(x<=tree[rt].l&&y>=tree[rt].r)
{
ans+=tree[rt].sum;
return ;
}
int mid=tree[rt].Mid();
if(y<=mid)
Query(ans,rt*2,x,y);
else
{
if(x>mid)
Query(ans,rt*2+1,x,y);
else
{
Query(ans,rt*2,x,mid);
Query(ans,rt*2+1,mid+1,y);
}
}

}

int main()
{
int count=1;
int t;
int n;
scanf("%d",&t);
while(t--)
{
printf("Case %d:\n",count++);
scanf("%d",&n);
build(1,1,n);
char str[100];
while(scanf("%s",str))
{
if(str[0]=='E')
break;
int x,y;
scanf("%d%d",&x,&y);
if(str[0]=='A')
Add(1,x,y);
if(str[0]=='S')
Add(1,x,-y);
if(str[0]=='Q')
{
int ans=0;
Query(ans,1,x,y);
printf("%d\n",ans);
}

}

}
}