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);

}