HDU.1166 敌兵布阵 (线段树 单点更新 区间查询)

HDU.1166 敌兵布阵 (线段树 单点更新 区间查询)

题意分析

加深理解，重写一遍

代码总览

#include <bits/stdc++.h>
#define nmax 100000
using namespace std;
struct Tree{
    int l,r,val;
    int lazy;
    int mid(){
        return (l+r)>>1;
    }
};
Tree tree[nmax<<2];
int num[nmax<<2];
void PushUp(int rt)
{
    tree[rt].val = tree[rt<<1].val + tree[rt<<1|1].val;
}
void Build(int l, int r, int rt)
{
    tree[rt].l = l; tree[rt].r = r;
    tree[rt].val = tree[rt].lazy = 0;
    if(l == r){
        tree[rt].val = num[l];
        return;
    }
    Build(l,tree[rt].mid(),rt<<1);
    Build(tree[rt].mid()+1,r,rt<<1|1);
    PushUp(rt);
}
void UpdatePoint(int val, int pos, int rt)
{
    if(tree[rt].l == tree[rt].r){
        tree[rt].val+=val;
        return;
    }
    if(pos<= tree[rt].mid()) UpdatePoint(val,pos,rt<<1);
    else UpdatePoint(val,pos,rt<<1|1);
    PushUp(rt);
}
int Query(int l,int r,int rt)
{
    if(l>tree[rt].r || r<tree[rt].l) return 0;
    if(l <= tree[rt].l && tree[rt].r <= r) return tree[rt].val;
    return Query(l,r,rt<<1) + Query(l,r,rt<<1|1);
}
int T,N,a,b;
char op[10];
int main()
{
    //freopen("in.txt","r",stdin);
    scanf("%d",&T);
    for(int i = 1;i<=T;++i){
        printf("Case %d:\n",i);
        scanf("%d",&N);
        for(int j = 1;j<=N;++j) scanf("%d",&num[j]);
        Build(1,N,1);
        while(scanf(" %s",op) && op[0] != 'E'){
            scanf("%d %d",&a,&b);
            if(op[0] == 'Q'){
                printf("%d\n",Query(a,b,1));
            }else if(op[0] == 'A'){
                UpdatePoint(b,a,1);
            }else{
                UpdatePoint(-b,a,1);
            }
        }

    }
    return 0;
}