HDU 1754 I Hate It

Simple segment tree;

The portal:http://acm.hdu.edu.cn/showproblem.php?pid=1754

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

using namespace std;

const int MAXN = 200005;

struct Node {
	int value;
	int Left;
	int Right;
}Segment_Tree[MAXN<<2];

int a[MAXN];
int cnt ;

void Build_Tree(int Left,int Right,int Now) {
	Segment_Tree[Now].Left = Left;
	Segment_Tree[Now].Right = Right;
	if(Left == Right) {
		Segment_Tree[Now].value = a[cnt++];
		return ;
	}
	int Mid = (Left + Right) >> 1;
	Build_Tree(Left,Mid,Now<<1);
	Build_Tree(Mid+1,Right,Now<<1|1);
	Segment_Tree[Now].value = max(Segment_Tree[Now<<1].value,Segment_Tree[Now<<1|1].value);
}

void Update_Tree(int Left,int Right,int Now,int position,int change_value) {
	if(Left == Right) {
		Segment_Tree[Now].value = change_value;
		return;
	}
	int Mid = (Left + Right) >> 1;
	if(position > Mid) {
		Update_Tree(Mid+1,Right,Now<<1|1,position,change_value);
	}
	else {
		Update_Tree(Left,Mid,Now<<1,position,change_value);
	}
	Segment_Tree[Now].value = max(Segment_Tree[Now<<1].value,Segment_Tree[Now<<1|1].value);
}

int Query_Tree(int Left,int Right,int Now,int Left_Edge,int Right_Edge) {
	int Query_Ans = 0;
	if(Left >= Left_Edge && Right <= Right_Edge) {
		return Segment_Tree[Now].value;
	}
	int Mid = (Left + Right) >> 1;
	if(Mid >= Left_Edge) {
		Query_Ans = max(Query_Ans,Query_Tree(Left,Mid,Now<<1,Left_Edge,Right_Edge));
	}
	if(Mid < Right_Edge) {
		Query_Ans = max(Query_Ans,Query_Tree(Mid+1,Right,Now<<1|1,Left_Edge,Right_Edge));
	}
	return Query_Ans;
}

void Deal_with() {
	int n,m;
	while(~scanf("%d %d",&n,&m)) {
		for(int i = 1 ; i <= n ; i++) {
			scanf("%d",a+i);
		}
		cnt = 1;
		Build_Tree(1,n,1);
		char tempc;
		int position,value;
		for(int i = 1 ; i <= m ; i++) {
			getchar();
			scanf("%c %d %d",&tempc,&position,&value);
			if(tempc == 'U') {
				Update_Tree(1,n,1,position,value);
			}
			else {
				printf("%d\n",Query_Tree(1,n,1,position,value));
			}
		}
	}
}

int main(void) {
	//freopen("a.in","r",stdin);
	Deal_with();
	return 0;
}