【POJ】3667 Hotel

#include<cstdio>
#define MAX(a,b) ((a)>(b)?(a):(b))
#define MAXN 50010
struct node
{
    int right,left,val;
};
node tree[MAXN<<2];
int lazy[MAXN<<2];
void Build(int L,int R,int rt)
{
    lazy[rt]=-1;
    tree[rt].left=tree[rt].right=tree[rt].val=R-L+1;
    if(L!=R)
    {
        int mid=(L+R)>>1;
        Build(L,mid,rt<<1);
        Build(mid+1,R,rt<<1|1);
    }
}
inline void PushDown(int mid,int L,int R,int rt)
{
    if(lazy[rt]!=-1)
    {
        lazy[rt<<1]=lazy[rt<<1|1]=lazy[rt];
        lazy[rt]^=1;
        tree[rt<<1].left=tree[rt<<1].right=tree[rt<<1].val=(mid-L+1)*lazy[rt];
        tree[rt<<1|1].left=tree[rt<<1|1].right=tree[rt<<1|1].val=(R-mid)*lazy[rt];
        lazy[rt]=-1;
    }
}
int Query(int x,int L,int R,int rt)
{
    if(L==R)
        return L;
    int mid=(L+R)>>1;
    PushDown(mid,L,R,rt);
    if(tree[rt<<1].val>=x)
        return Query(x,L,mid,rt<<1);
    else if(tree[rt<<1].right+tree[rt<<1|1].left>=x)
        return mid-tree[rt<<1].right+1;
    else
        return Query(x,mid+1,R,rt<<1|1);
}
inline void PushUp(int mid,int L,int R,int rt)
{
    tree[rt].left=tree[rt<<1].left;
    tree[rt].right=tree[rt<<1|1].right;
    if(tree[rt].left==mid-L+1)
        tree[rt].left+=tree[rt<<1|1].left;
    if(tree[rt].right==R-mid)
        tree[rt].right+=tree[rt<<1].right;
    tree[rt].val=MAX(tree[rt<<1].val,tree[rt<<1|1].val);
    tree[rt].val=MAX(tree[rt].val,tree[rt<<1].right+tree[rt<<1|1].left);
}
void Update(int x,int y,int val,int L,int R,int rt)
{
    if(x<=L&&R<=y)
    {
        lazy[rt]=val;
        tree[rt].left=tree[rt].right=tree[rt].val=(R-L+1)*(val^1);
    }
    else
    {
        int mid=(L+R)>>1;
        PushDown(mid,L,R,rt);
        if(mid>=x)
            Update(x,y,val,L,mid,rt<<1);
        if(y>mid)
            Update(x,y,val,mid+1,R,rt<<1|1);
        PushUp(mid,L,R,rt);
    }
}
int main()
{
    int n,m,type,x,y;
    while(~scanf("%d%d",&n,&m))
    {
        Build(1,n,1);
        while(m--)
        {
            scanf("%d%d",&type,&x);
            if(type==1)
            {
                if(tree[1].val<x)
                    puts("0");
                else
                {
                    y=Query(x,1,n,1);
                    printf("%d\n",y);
                    Update(y,y+x-1,1,1,n,1);
                }
            }
            else
            {
                scanf("%d",&y);
                Update(x,x+y-1,0,1,n,1);
            }
        }
    }
    return 0;
}