HDU1754-ZKW线段树

单点更新，区间最值

HDU 1754

//
// Created by helica on 2018/3/18.
//

//zkw线段树 单点修改 区间求最值
//HDU 1754

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>

using namespace std;
const int N =  + ;

int M = ;
int T[N<<];

void change(int x, int v){
    T[M+x] = v;
    for(int p= (M+x)>>;p;p>>=) T[p] = max(T[p<<], T[p<<|]);
}

int query(int s, int t){
    int ans = -;
    for (s=M+s-,t=M+t+; s^t^; s>>=, t>>=) {
        if (~s&) ans = max(ans, T[s^]);
        if ( t&) ans = max(ans, T[t^]);
    }
    return ans;
}

int main(){
    int n,q,op,s,t;
    while(~scanf("%d %d", &n, &q)){
        memset(T, , sizeof T);

        for(M=;M<n;M<<=);
        for (int i=,tmp;i<n;i++) {
            scanf("%d", &tmp);
            change(i+, tmp);
        }

        for(int i=;i<q;i++){
            char op[];
            scanf("%s %d %d", op, &s, &t);
            if(op[] == 'U'){
                change(s, t);
            }else if(op[] == 'Q'){
                printf("%d\n", query(s, t));
            }
        }
    }
}