UESTC 1227 & POJ 3667 Hotel

非常细腻的线段树题目啊，后来还是有个细节写错了，查了一个晚上。。就不分析了。

代码：

#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[*N];

int n,m;

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

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

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

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

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 == )   //如果当前要入住
        {
            tree[rt].ls = tree[rt].rs = tree[rt].ms = ;
            tree[rt].pos = l;
            tree[rt].mark = ;
        }
        else  //如果当前要退房
        {
            tree[rt].ls = tree[rt].rs = tree[rt].ms = r-l+;
            tree[rt].pos = l;
            tree[rt].mark = ;
        }
        return;
    }
    update(l,r,rt);
    int mid = (l+r)/;
    in_out(l,mid,aa,bb,flag,*rt);
    in_out(mid+,r,aa,bb,flag,*rt+);

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

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

    if(tree[rt].ms == tree[*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[*rt].pos;  //则起点置为左子树的起点

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

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

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