HDU 1890 / BZOJ 3506 Robot Sort 题解

题意：给一个初始序列，有n个数。现在要对它们进行排序。第i次通过区间翻转将第i小的数翻转到正确的位置上（即第i位），输出旋转前i的位置。

（语死早，凑合理解一下。。）

思路就是每次将第i小的数splay到根，统计一下再删除。答案就是左子树大小加上已删除的数的个数。

然后这题是有可能出现重复的数字的。。有重复的话在前面的比较小。（这点我调了1h

#include<cstdio>
#include<algorithm>
const int MAXN=100000+10;
const int INF=~0U>>1;
int a[MAXN];
struct Node{
    int s,v;
    bool rev;
    Node* p,*ch[2],*minn;
    Node() {s=rev=0;v=INF;minn=this;}
    inline bool d() {return p->ch[1]==this;}
    inline void maintain();
    inline void revIt()
    {
        std::swap(ch[0],ch[1]);
        rev^=1;
    }
    inline void setc(Node* t,bool d)
    {
        ch[d]=t;
        t->p=this;
    }
    inline void pushdown();
}Tnull,*null=&Tnull;
Node mem[MAXN],*C=mem;
Node* root;
struct met{
    Node* temp;
    int pos;
    bool operator<(const met& rhs)const
    {
        return temp->v < rhs.temp->v ||(rhs.temp->v == temp->v && pos<rhs.pos);
    }
}h[MAXN];
inline Node* Min(Node* a,Node* b)
{
    return a->v <= b->v ?a:b;
}
inline void Node::pushdown()
{
    if(rev)
    {
        if(ch[0]!=null) ch[0]->revIt();
        if(ch[1]!=null) ch[1]->revIt();
        rev=0;
    }
}
inline void Node::maintain()
{
    s=ch[0]->s+ch[1]->s+1;
    minn=Min(Min(ch[0]->minn,this),ch[1]->minn);
}
inline void init()
{
    C=mem;
}
inline Node* NewNode(int v)
{
    C->v=v;C->s=1;
    C->ch[0]=C->ch[1]=null;
    return C++;
}
Node* build(int l,int r) //[l,r)
{
    if(l>=r) return null;
    int m=l+r>>1;
    Node* t=NewNode(a[m]);
    h[m].temp=t;h[m].pos=m;
    Node* L=build(l,m),*R=build(m+1,r);
    t->setc(L,0);t->setc(R,1);
    t->maintain();
    return t;
}
void rot(Node* t)
{
    Node* p=t->p;
    p->pushdown();t->pushdown();
    int d=t->d();
    p->p->setc(t,p->d());
    p->setc(t->ch[d^1],d);
    t->setc(p,d^1);
    p->maintain();
    if(p==root) root=t;
}
void splay(Node* t,Node* f=null)
{
    while(t->p!=f)
    {
        if(t->p->p==f) rot(t);
        else
            t->d()==t->p->d()?(rot(t->p),rot(t)):(rot(t),rot(t));
    }
    t->maintain();
}
Node* select(int k)
{
    for(Node* t=root;;)
    {
        t->pushdown();
        int s=t->ch[0]->s;
        if(k==s) return t;
        if(k>s) k-=s+1,t=t->ch[1];
        else t=t->ch[0];
    }
}
inline void splay(int k,Node* f=null)
{
    splay(select(k),f);
}
Node*& get(int l,int r)
{
    Node* L=select(l-1);
    Node* R=select(r);
    splay(L);
    splay(R,L);
    return R->ch[0];
}
int DelMin(int i)
{
    splay(h[i].temp);
    int s=root->ch[0]->s;
    Node*& t=get(1,s);
    t->revIt();
    splay(s-1);
    splay(s+1,root);
    root->ch[1]->ch[0]=null;
    root->ch[1]->maintain();
    root->maintain();
    return s;
}
int n;
int main()
{
    while(scanf("%d",&n)!=EOF && n)
    {
        a[0]=a[n+1]=INF;
        init();
        for(int i=1;i<=n;++i) scanf("%d",a+i);
        root=build(0,n+2);
        root->p=null;
        std::sort(h+1,h+n+1);
        for(int i=0;i<n;++i)
        {
            printf("%d%c",DelMin(i+1)+i,i==n-1?'\n':' ');
        }
    }
    return 0;
}