5 6
1 2 3 4 5
Q 1 5
U 3 6
Q 3 4
Q 4 5
U 2 9
Q 1 5
  
  

  
  

   
   5
6
5
9


   
   
 
    
 
     Hint 
    
Huge input,the C function scanf() will work better than cin 
   
   
    
  
  

和1166题的不同主要是非叶子节点,存放的是两个子节点的较大值

Query两种写法...我还是觉得注释掉的容易想......

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <iostream>
#include <algorithm>
using namespace std;

const int MAXN=200010;
int grade[MAXN<<2];

void PushUp(int ret)
{
     grade[ret]=grade[ret<<1]>=grade[ret<<1|1]?grade[ret<<1]:grade[ret<<1|1];
}

void BuildTree(int left,int right,int ret)
{
    if(left==right)
    {
        scanf("%d",grade+ret);
        return ;
    }    
    int mid=(left+right)>>1;
    BuildTree(left,mid,ret<<1);
    BuildTree(mid+1,right,ret<<1|1);
    PushUp(ret);
}

void Update(int target,int score,int left,int ret)
{
    if(left==right)
    {
        grade[ret]=score;
        return ;
    }
    int mid=(left+right)>>1;
    if(target<=mid)
        Update(target,score,left,ret<<1);
    else
        Update(target,mid+1,ret<<1|1);
    PushUp(ret);
}

/*
int Query(int L,int R,int ret)
{
    if(L<=left && right<=R)
        return grade[ret];
    int mid=(left+right)>>1;
    if(R<=mid)
        return Query(L,R,ret<<1);
    else if(mid<L)
        return Query(L,ret<<1|1);
    else
        return max(Query(L,ret<<1),Query(L,ret<<1|1));
}
*/

int Query(int L,int ret)
{
    if(L<=left && right<=R)
        return grade[ret];
    int mid=(left+right)>>1;
    int tmp=0,tmpmax=-100;
    if(L<=mid)
    {
        tmp=Query(L,ret<<1);
        tmpmax=tmp>=tmpmax?tmp:tmpmax;
    }
    if(mid<R)
    {
        tmp=Query(L,ret<<1|1);
        tmpmax=tmp>=tmpmax?tmp:tmpmax;
    }
    return tmpmax;
}

int main()
{
    freopen("1754.in","r",stdin);
//    freopen("1754.out","w",stdout);
    int N,M,a,b;
    char tmp;
    while(scanf("%d%d",&N,&M)!=EOF)
    {
        BuildTree(1,N,1);
        getchar();
        while(M--)
        {
            scanf("%c%d%d",&tmp,&a,&b);
            getchar();
            if(tmp=='U')
                Update(a,b,1,1);
            else if(tmp=='Q')
                printf("%d\n",Query(a,1));
        }
    }
    return 0;
}