<span>HDU1754 I Hate It（线段树基础题单节点更新区间查询）</span>

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <queue>
#include <cmath>
#include <algorithm>
using namespace std;
#define M 200005
#define ls node<<1,l,m
#define rs node<<1|1,m+1,r
int n,m,tree[M*4];
void buildtree(int node,int l,int r)
{
    if(l==r) scanf("%d",&tree[node]);
    else
    {
        int m=(l+r)>>1;
        buildtree(ls);
        buildtree(rs);
        tree[node]=max(tree[node<<1],tree[node<<1|1]);
    }
}
int query(int node,int l,int r,int L,int R)
{
    if(L<=l&&r<=R) return tree[node];
    int p=0,m=(l+r)>>1;
    if(m>=L) p=query(ls,L,R);
    if(m<R) p=max(p,query(rs,L,R));
    return p;
}
void update(int node,int l,int r,int ind,int add)
{
    if(l==r) tree[node]=add;
    else
    {
        int m=(l+r)>>1;
        if(m>=ind) update(ls,ind,add);
        else update(rs,ind,add);
        tree[node]=max(tree[node<<1],tree[node<<1|1]);
    }
}
int main()
{
    //freopen("in.txt","r",stdin);
    while(~scanf("%d%d",&n,&m))
    {
        buildtree(1,1,n);
        char s[2];
        int a,b;
        while(m--)
        {
            scanf("%s%d%d",s,&a,&b);
            if(s[0]=='Q') printf("%d\n",query(1,1,n,a,b));
            else update(1,1,n,a,b);
        }
    }
    return 0;
}