【Luogu】P2894酒店Hotel（线段树）

　　题目链接

　　我好蒻啊   题题看题解

　　线段树维护从左端点开始的最长连续空房、右端点结束的最长连续空房、整段区间的最长连续空房、区间非空房的个数。

　　http://blog.csdn.net/qq_39553725/article/details/77604572    此处题解。

　　

#include<cstdio>
#include<cmath>
#include<algorithm>
#include<cstring>
#include<iostream>
#include<cctype>
#define left (rt<<1)
#define right (rt<<1|1)
#define mid ((l+r)>>1)
#define lson l,mid,left
#define rson mid+1,r,right
#define root 1,n,1
#define len (r-l+1)

inline long long max(long long a,long long b){    return a>b?a:b;    }

inline long long read(){
    long long num=0,f=1;
    char ch=getchar();
    while(!isdigit(ch)){
        if(ch=='-')    f=-1;
        ch=getchar();
    }
    while(isdigit(ch)){
        num=num*10+ch-'0';
        ch=getchar();
    }
    return num*f;
}

int tag[1000010];
struct Node{
    int linel,liner,linem,sum;
}tree[1000010];

inline void pushup(int rt,int m){
    tree[rt].linel=tree[left].sum?tree[left].linel:(m-(m>>1))+tree[right].linel;
    tree[rt].liner=tree[right].sum?tree[right].liner:(m>>1)+tree[left].liner;
    tree[rt].sum=tree[left].sum+tree[right].sum;
    tree[rt].linem=max(tree[rt].linel,tree[rt].liner);
    tree[rt].linem=max(tree[rt].linem,tree[left].liner+tree[right].linel);
    tree[rt].linem=max(tree[rt].linem,max(tree[left].linem,tree[right].linem));
}

inline void pushdown(int rt,int m){
    if(!tag[rt])    return;
    if(tag[rt]==1){
        tree[left].linel=tree[left].liner=tree[left].linem=0;tree[left].sum=(m-(m>>1));
        tree[right].linel=tree[right].liner=tree[right].linem=0;tree[right].sum=(m>>1);
        tag[left]=tag[right]=1;
        tag[rt]=0;
    }
    if(tag[rt]==2){
        tree[left].linel=tree[left].liner=tree[left].linem=(m-(m>>1));    tree[left].sum=0;
        tree[right].linel=tree[right].liner=tree[right].linem=(m>>1);    tree[right].sum=0;
        tag[left]=tag[right]=2;
        tag[rt]=0;
    }
}

void build(int l,int r,int rt){
    if(l==r){
        tree[rt]=(Node){1,1,1,0};
        return;
    }
    build(lson);
    build(rson);
    pushup(rt,len);
}

void clear(int from,int to,int l,int r,int rt){
    if(from<=l&&to>=r){
        tree[rt]=(Node){    len,len,len,0    };
        tag[rt]=2;
        return;
    }
    pushdown(rt,len);
    if(from<=mid)    clear(from,to,lson);
    if(to>mid)        clear(from,to,rson);
    pushup(rt,len);
    return;
}

void update(int from,int to,int l,int r,int rt){
    if(from<=l&&to>=r){
        tree[rt]=(Node){    0,0,0,len    };
        tag[rt]=1;
        return;
    }
    pushdown(rt,len);
    if(from<=mid)    update(from,to,lson);
    if(to>mid)        update(from,to,rson);
    pushup(rt,len);
    return;
}

int query(int size,int l,int r,int rt){
    if(tree[rt].linem<size)    return 0x7fffffff;
    pushdown(rt,len);
    if(tree[left].linem>=size)    return query(size,lson);
    if(tree[right].linel+tree[left].liner>=size)    return mid-tree[left].liner+1;
    if(tree[right].linem>=size)    return query(size,rson);
    return 0x7fffffff;
}

int main(){
    int n=read(),m=read();
    build(root);
    for(int i=1;i<=m;++i){
        int opt=read();
        if(opt==1){
            int x=read();
            int ans=query(x,root);
            if(ans==0x7fffffff){
                printf("0\n");
                continue;
            }
            printf("%d\n",ans);
            update(ans,ans+x-1,root);
        }
        if(opt==2){
            int x=read(),y=read();
            clear(x,x+y-1,root);
        }
    }
    return 0;
}