1754 I Hate It

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

线段树功能：

#include<cstdio>
#include<cstdlib>
#include<cmath>
#include<cstring>
#define MAXN 200005
int seg_tree[MAXN<<2];
void build_tree(int l,int r,int id);
int query_tree(int left,int right,int l,int r,int id);
void update_point_tree(int left,int right,int value,int l,int r,int id);
void push_up_tree(int id);
int main()
{
int tcase,n,i,left,right,value,m;
char str[20];
while(scanf("%d%d",&n,&m)==2)
{
build_tree(1,n,1);
while(m--)
{
scanf("%s",str);
if(str[0]=='Q')
{
scanf("%d%d",&left,&right);
printf("%d\n",query_tree(left,right,1,n,1));
}
if(str[0]=='U')
{
scanf("%d%d",&left,&value);
update_point_tree(left,right,value,1,n,1);
}
}
}
}
void build_tree(int l,int r,int id)
{
if(l==r)
{
scanf("%d",&seg_tree[id]);
return ;
}
int mid=(l+r)/2;
build_tree(l,mid,id<<1);
build_tree(mid+1,r,id<<1|1);
push_up_tree(id);

}
int query_tree(int left,int right,int l,int r,int id)
{
if(left<=l&&right>=r)
return seg_tree[id];
int mid=(l+r)>>1,ret0=0,ret1=0;
if(left<=mid)
ret0=query_tree(left,right,l,mid,id<<1);
if(right>mid)
ret1=query_tree(left,right,mid+1,r,id<<1|1);
return ret0>=ret1?ret0:ret1;
}
void update_point_tree(int left,int right,int value,int l,int r,int id)
{
if(l==r)
{    seg_tree[id]=value;
return ;}
int mid=(l+r)>>1;
if(left<=mid)
update_point_tree(left,right,value,l,mid,id<<1);
else 
update_point_tree(left,right,value,mid+1,r,id<<1|1);
push_up_tree(id);
}
void push_up_tree(int id)
{
int temp1,temp2;
temp1=seg_tree[id<<1];
temp2=seg_tree[id<<1|1];
seg_tree[id]=(temp1>=temp2?temp1:temp2);
}