【USACO 2008FEB】 旅馆

【题目链接】

点击打开链接

【算法】

线段树

对于一个节点，记录它从左端点延伸的最多的空房间的个数，从右端点延伸的最多的空房间个数，和该区间最多的连续

空房间个数

【代码】

#include<bits/stdc++.h>
using namespace std;
#define MAXN 50010

int n,m,opt,pos,x,d;

struct SegmentTree
{
        struct Node
        {
                int l,r,lm,rm,mx,tag;
        } Tree[MAXN*];
        inline void build(int index,int l,int r)
        {
                int mid;
                Tree[index].l = l;
                Tree[index].r = r;
                Tree[index].lm = Tree[index].rm = Tree[index].mx = r - l + ;
                Tree[index].tag = -;
                if (l == r) return;
                mid = (l + r) >> ;
                build(index<<,l,mid);
                build(index<<|,mid+,r);
        }
        inline void pushdown(int index)
        {
                int ql = Tree[index].l,qr = Tree[index].r;
                int mid = (ql + qr) >> ;
                if (ql == qr) return;
                if (Tree[index].tag == )
                {
                        Tree[index<<].lm = Tree[index<<].rm = Tree[index<<].mx = mid - ql + ;
                        Tree[index<<|].lm = Tree[index<<|].rm = Tree[index<<|].mx = qr - mid;
                        Tree[index<<].tag = Tree[index<<|].tag = ;
                        Tree[index].tag = -;
                }
                if (Tree[index].tag == )
                {
                        Tree[index<<].lm = Tree[index<<].rm = Tree[index<<].mx = ;
                        Tree[index<<|].lm = Tree[index<<|].rm = Tree[index<<|].mx = ;
                        Tree[index<<].tag = Tree[index<<|].tag = ;
                        Tree[index].tag = -;
                }
        }
        inline void update(int index)
        {
                int ql = Tree[index].l,qr = Tree[index].r;
                int mid = (ql + qr) >> ;
                if (Tree[index<<].lm == mid - ql + ) Tree[index].lm = Tree[index<<].lm + Tree[index<<|].lm;
                else Tree[index].lm = Tree[index<<].lm;
                if (Tree[index<<|].rm == qr - mid) Tree[index].rm = Tree[index<<|].rm + Tree[index<<].rm;
                else Tree[index].rm = Tree[index<<|].rm;
                Tree[index].mx = max(max(Tree[index<<].mx,Tree[index<<|].mx),Tree[index<<].rm+Tree[index<<|].lm);
        }
        inline void modify(int index,int l,int r,int val)
        {
                int mid,ql,qr;
                if (Tree[index].l == l && Tree[index].r == r)
                {
                        Tree[index].lm = Tree[index].rm = Tree[index].mx = (val ^ ) * (r - l + );
                        Tree[index].tag = val;
                } else
                {
                        pushdown(index);
                        ql = Tree[index].l;
                        qr = Tree[index].r;
                        mid = (ql + qr) >> ;
                        if (mid >= r) modify(index<<,l,r,val);
                        else if (mid +  <= l) modify(index<<|,l,r,val);
                        else
                        {
                                modify(index<<,l,mid,val);
                                modify(index<<|,mid+,r,val);
                        }
                        update(index);
                }
        }
        inline int query_pos(int index,int d)
        {
                int mid,ql,qr;
                ql = Tree[index].l; qr = Tree[index].r;
                mid = (ql + qr) >> ;
                if (ql == qr) return ql;
                pushdown(index);
                if (Tree[index<<].mx >= d) return query_pos(index<<,d);
                else if (Tree[index<<].rm + Tree[index<<|].lm >= d) return mid - Tree[index<<].rm + ;
                else return query_pos(index<<|,d);
        }
        inline int query()
        {
                return Tree[].mx;
        }
} T;

template <typename T> inline void read(T &x)
{
    int f = ; x = ;
    char c = getchar();
    for (; !isdigit(c); c = getchar()) { if (c == '-') f = -f; }
    for (; isdigit(c); c = getchar()) x = (x << ) + (x << ) + c - '';
    x *= f;
}
template <typename T> inline void write(T x)
{
    if (x < )
    {
        putchar('-');
        x = -x;
    }
    if (x > ) write(x/);
    putchar(x%+'');
}
template <typename T> inline void writeln(T x)
{
    write(x);
    puts("");
}

int main() {

        read(n); read(m);
        T.build(,,n);
        while (m--)
        {
                read(opt);
                if (opt == )
                {
                        read(d);
                        if (T.query() < d) writeln();
                        else
                        {
                                pos = T.query_pos(,d);
                                writeln(pos);
                                T.modify(,pos,pos+d-,);
                        }
                } else
                {
                        read(x); read(d);
                        T.modify(,x,x+d-,);
                }
        }

        return ;

}