HDU 1890 Robotic Sort

试水splay

思路：把需要排的的节点splay到根（预处理保存这些节点），就可得到答案（左子树节点的数量）

            更新的时候就是把当前序列第ith个节点splay到根，刚需要排的节点splay到根的右子树，跟新根的右子树的左子树

题外话： 一开始写的时候傻了，硬是自己去找到当前要排序的节点，然后splay到根。 还有自己写的一些函数忘记pushdown了。。。

#include<stdio.h>#include<string.h>#include<algorithm>using namespace std;const int maxn = 1e5+100;const int inf = 0x7FFFFFFF;struct Snode{    Snode *p,*c[2];    int key,sz;    bool rev;    bool getlr(){return p->c[1]==this;}    Snode *link(int w,Snode *x,Snode *null){c[w]=x; if(x!=null) x->p=this; return this;}}S[maxn],*sa[maxn],*root,*null;struct node{    int x,n;}a[maxn];int n,tot,pos[maxn];bool cmp1(node a,node b){    if(a.x == b.x) return a.n<b.n;    return a.x<b.x;}bool cmp2(node a,node b){    return a.n < b.n;}Snode *NewNode(int key, Snode *p){    Snode *e = S + ++tot;    e->key = key; e->p = p;    e->sz = 1; e->rev = 0;    e->c[0] = e->c[1] = null;    return e;}void Update_Rev(Snode *x){    if(x==null) return;    swap(x->c[0],x->c[1]);    x->rev ^= 1;}void pushup(Snode *x){    if(x==null) return;    x->sz = x->c[0]->sz + x->c[1]->sz + 1;}void pushdown(Snode *x){    if(x==null) return;    if(x->rev)    {        Update_Rev(x->c[0]);        Update_Rev(x->c[1]);        x->rev = 0;    }}void rot(Snode *x){    Snode *q = x->p->p;    int o = x->getlr();    x->link(!o, x->p->link(o, x->c[!o], null), null);    pushup(x->p);    if(q!=null) q->link(q->c[1]==x->p, x, null);    else {x->p = null;root = x;}}void splay(Snode *x, Snode *tar){    while(x->p!=tar && x->p->p!=tar)    {        pushdown(x->p->p);        pushdown(x->p);        pushdown(x);        x->getlr()==x->p->getlr()?rot(x->p):rot(x),rot(x);    }    if(x->p!=tar)    {        pushdown(x->p);        pushdown(x);        rot(x);    }    pushup(x);}Snode* succ(Snode *x)  //寻找后继{    if(x==null) return null;    pushdown(x);    x = x->c[1];    pushdown(x);    while(x->c[0] != null) {x = x->c[0]; pushdown(x);}    return x;}#define lsz x->c[0]->szvoid select(int k, Snode *y){    Snode *x = root;    pushdown(x);    while(lsz + 1 != k)    {        if(k<=lsz)            x=x->c[0];        else        {            k -= lsz + 1;            x = x->c[1];        }        pushdown(x);    }    splay(x, y);}Snode* build(int l,int r,Snode *p){    if(l > r) return null;    int m = (l+r)/2;    Snode *x = NewNode(a[m].x,p);    sa[pos[m]] = x;    x->c[0] = build(l,m-1,x);    x->c[1] = build(m+1,r,x);    pushup(x);    return x;}void Reserve(int L){    Snode *x = succ(root);    select(L, null); splay(x, root);    Update_Rev(root->c[1]->c[0]);    splay(root->c[1]->c[0], null);}void init(){    tot = 0;    null = NewNode(inf, 0);    null->c[0] = null->c[1] = null;    null->sz = 0;    root = null;}int main(){    while(scanf("%d",&n),n)    {        init();        a[0].x = pos[0] = a[n+1].x = pos[n+1] =maxn-1;        for(int i=1;i<=n;i++)        {            scanf("%d",&a[i].x);            a[i].n = i;        }        sort(a+1,a+n+1,cmp1);        for(int i=1;i<=n;i++)  pos[a[i].n] = i;        sort(a+1,a+n+1,cmp2);        root = build(0, n+1, null);        for(int i=1;i<=n;i++)        {            splay(sa[i], null);            printf("%d%s",root->c[0]->sz,i==n?"\n":" ");            Reserve(i);        }    }    return 0;}