UESTC 1227 & POJ 3667 Hotel

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <utility>
#include <cstdlib>
using namespace std;
#define N 80011

struct node
{
int ls,rs,ms;
int pos;
int mark;   // 0: unsure  1: all-empty  2: all-full
}tree[4*N];

int n,m;

void build(int l,int r,int rt)
{
tree[rt].ls = tree[rt].rs = tree[rt].ms = r-l+1;
tree[rt].pos = l;
if(l == r)
{
return;
}
int mid = (l+r)/2;
build(l,mid,2*rt);
build(mid+1,r,2*rt+1);
}

int if_all_empty(int l,int r,int rt)
{
if(tree[rt].ls == r-l+1)
return 1;
return 0;
}

void update(int l,int r,int rt)
{
if(!tree[rt].mark)
return;
if(tree[rt].mark == 1)  //全空，则下传给左右子树
{
int len = r-l+1;
tree[2*rt].ls = tree[2*rt].rs = tree[2*rt].ms = (len+1)/2;
tree[2*rt].pos = l;
tree[2*rt+1].ls = tree[2*rt+1].rs = tree[2*rt+1].ms = len/2;
tree[2*rt+1].pos = (l+r)/2+1;
tree[2*rt].mark = tree[2*rt+1].mark = 1;
}
else if(tree[rt].mark == 2)  //全满，则下传给左右子树
{
tree[2*rt].ls = tree[2*rt].rs = tree[2*rt].ms = 0;
tree[2*rt].pos = l;
tree[2*rt+1].ls = tree[2*rt+1].rs = tree[2*rt+1].ms = 0;
tree[2*rt+1].pos = (l+r)/2+1;
tree[2*rt].mark = tree[2*rt+1].mark = 2;
}
tree[rt].mark = 0;   // not "== 0"
}

int query(int l,int r,int dis,int rt)
{
update(l,r,rt);
if(tree[rt].ms<dis)
return 0;
if(tree[rt].ms == dis)
return tree[rt].pos;
int mid = (l+r)/2;
if(tree[2*rt].ms>=dis)
return query(l,mid,dis,2*rt);
if(tree[2*rt].rs + tree[2*rt+1].ls>=dis)
return mid - tree[2*rt].rs + 1;
return query(mid+1,r,dis,2*rt+1);
}

void in_out(int l,int r,int aa,int bb,int flag,int rt)   //flag == 1: insert   else  quit
{
if(aa>r||bb<l)
return;
if(aa<=l&&bb>=r)
{
if(flag == 1)   //如果当前要入住
{
tree[rt].ls = tree[rt].rs = tree[rt].ms = 0;
tree[rt].pos = l;
tree[rt].mark = 2;
}
else  //如果当前要退房
{
tree[rt].ls = tree[rt].rs = tree[rt].ms = r-l+1;
tree[rt].pos = l;
tree[rt].mark = 1;
}
return;
}
update(l,r,rt);
int mid = (l+r)/2;
in_out(l,mid,aa,bb,flag,2*rt);
in_out(mid+1,r,aa,bb,flag,2*rt+1);

tree[rt].ls = tree[2*rt].ls;
if(if_all_empty(l,mid,2*rt))
tree[rt].ls += tree[2*rt+1].ls;
tree[rt].rs = tree[2*rt+1].rs;
if(if_all_empty(mid+1,r,2*rt+1))
tree[rt].rs += tree[2*rt].rs;

tree[rt].ms = max(tree[2*rt].rs+tree[2*rt+1].ls,max(tree[2*rt].ms,tree[2*rt+1].ms));

if(tree[rt].ms == tree[2*rt].ms)   //如果当前区间最大空房数等于左子树最大空房数
tree[rt].pos = tree[2*rt].pos;  //则起点置为左子树的起点

else if(tree[rt].ms == tree[2*rt].rs + tree[2*rt+1].ls)  //同理
tree[rt].pos = mid - tree[2*rt].rs + 1;

else
tree[rt].pos = tree[2*rt+1].pos;
}

int main()
{
scanf("%d%d",&n,&m);
memset(tree,0,sizeof(tree));
build(1,n,1);
int i,flag;
int x,dis;
for(i=0;i<m;i++)
{
scanf("%d",&flag);
if(flag == 1)
{
scanf("%d",&dis);
int ans = query(1,n,dis,1);
printf("%d\n",ans);
if(ans)
in_out(1,n,ans,ans+dis-1,1,1);
}
else if(flag == 2)
{
scanf("%d%d",&x,&dis);
in_out(1,n,x,x+dis-1,2,1);
}
}
return 0;
}