HDU1754 I Hate It，线段树

/*******************************************************************************
# Author : Neo Fung
# Email : neosfung@gmail.com
# Last modified: 2012-01-17 20:35
# Filename: HDU1754 I Hate It.cpp
# Description :
******************************************************************************/
#ifdef _MSC_VER
#define DEBUG
#endif

#include <fstream>
#include <stdio.h>
#include <iostream>
#include <string.h>
#include <string>
#include <limits.h>
#include <algorithm>
#include <math.h>
#include <numeric>
#include <functional>
#include <ctype.h>
#define L(x) (x<<1)
#define R(x) (x<<1|1)
#define MAX 200010
using namespace std;

struct NODE_T
{
int l,r,score;
}node[MAX*4];

void init()
{
memset(node,'\0',sizeof(node));
}

void build(const int &t,const int &l,const int &r)
{
node[t].l = l;
node[t].r = r;
node[t].score = -1;
if(l==r-1)
return;
int mid=(l+r)>>1;
build(L(t),l,mid);
build(R(t),mid,r);
}
void update(const int &t,const int &l,const int &r,const int score)
{
if(node[t].l==l && node[t].r==r)
{
node[t].score = score;
return;
}
int mid = (node[t].l+node[t].r)>>1;
if( l>=mid)
update(R(t),l,r,score);
else if(mid>=r)
update(L(t),l,r,score);
node[t].score = max(node[L(t)].score,node[R(t)].score);
}

int query(const int &t,const int &l,const int &r)
{
if(node[t].l>=l && node[t].r<=r)
return node[t].score;
int mid=(node[t].l+node[t].r)>>1;
if(l>=mid)
return query(R(t),l,r);
else if(r<=mid)
return query(L(t),l,r);
else
{
int a = query(L(t),l,mid);
int b = query(R(t),mid,r);
return max(a,b);
}
}

int main(void)
{
#ifdef DEBUG
freopen("../stdin.txt","r",stdin);
freopen("../stdout.txt","w",stdout);
#endif
int n,m;
int x,y;
char ch;

while(~scanf("%d%d",&n,&m))
{
init();
build(1,0,n+1);
for(int i=1;i<=n;++i)
{
scanf("%d",&x);
update(1,i,i+1,x);
}
while(m--)
{
getchar();
scanf("%c %d %d",&ch,&x,&y);
if(ch=='Q')
printf("%d\n",query(1,x,y+1));
else
update(1,x,x+1,y);
}
}

return 0;
}