2016夏季练习——线段树

来源：HDU1166

代码：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#define lson rt<<1
#define rson rt<<1|1
using namespace std;
const int MAXN = 50000+10;
int tree[MAXN<<2],a[MAXN];
int n;
char ch[10];
void pushup(int rt){
    tree[rt] = tree[lson] + tree[rson];
}
void build(int rt,int l,int r){
    if(l == r){
        tree[rt] = a[l];
        return ;
    }
    int mid = (l+r)>>1;
    build(lson,l,mid);
    build(rson,mid+1,r);
    pushup(rt);
}
void update(int rt,int l,int r,int pos,int data){
    //cout<<l<<" "<<r<<" "<<pos<<endl;
    if(l == pos &&  pos == r){
        tree[rt] += data;
        return ;
    }
    int mid = (l+r)>>1;
    if(pos<=mid) update(lson,l,mid,pos,data);
    else update(rson,mid+1,r,pos,data);
    pushup(rt);
}
int query(int rt,int l,int r,int left,int right){
    if(left<=l && r<=right){
        return tree[rt];
    }
    int mid = (l+r)>>1;
    int ans = 0;
    if(left<=mid) ans+=query(lson,l,mid,left,right);
    if(right>mid) ans+=query(rson,mid+1,r,left,right);
    return ans;
}
int main(){
    int T,nc=1;
    scanf("%d",&T);
    int x,y;
    while(T--){
        scanf("%d",&n);
        for(int i=1;i<=n;i++) scanf("%d",a+i);
        build(1,1,n);
        getchar();
        cout<<"Case "<<nc++<<":"<<endl;
        while(scanf("%s",ch)!=EOF){
            //cout<<"ch : "<<ch<<endl;
            if(ch[0] == 'E') break;
            if(ch[0] == 'A'){
                scanf("%d%d",&x,&y);
                update(1,1,n,x,y);
            }
            if(ch[0] == 'Q'){
                scanf("%d%d",&x,&y);
                cout<<query(1,1,n,x,y)<<endl;
            }
            if(ch[0] == 'S'){
                scanf("%d%d",&x,&y);
                update(1,1,n,x,-y);
            }
        }
    }
    return 0;
}