hdu 1890 Robotic SortI（splay区间旋转操作）

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=1890

题解：splay又一高级的功能，区间旋转这个是用线段树这些实现不了的，这题可以学习splay的旋转方法还有splay tree是按照中序来的，也就是说中序遍历后会得到原序列所以建树和线段树差不多稍微有点不一样。其实splay tree核心操作就是splay就是将某个点移到goal下面优化bst的操作。

#include <cstdio>
#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
const int M = 1e5 + 10;
int pre[M] , ch[M][2] , size[M] , rev[M] , tot , root;//rev类似懒惰标记表示该区间是否要旋转
void NewNode(int &r , int fa , int k) {
    r = k;
    pre[r] = fa;
    ch[r][0] = ch[r][1] = 0;
    size[r] = 1;
    rev[r] = 0;
}
void Rev(int r) {
    if(!r) return ;
    else {
        swap(ch[r][0] , ch[r][1]);
        rev[r] ^= 1;
    }
}//新的操作区间旋转
void push_up(int r) {
    size[r] = size[ch[r][0]] + size[ch[r][1]] + 1;
}
void push_down(int r) {
    if(rev[r]) {
        Rev(ch[r][0]);
        Rev(ch[r][1]);
        rev[r] = 0;
    }
}//新操作的push_down;
void Rotate(int x , int kind) {
    int y = pre[x];
    push_down(y);
    push_down(x);
    ch[y][!kind] = ch[x][kind];
    pre[ch[x][kind]] = y;
    if(pre[y]) ch[pre[y]][ch[pre[y]][1] == y] = x;
    pre[x] = pre[y];
    ch[x][kind] = y;
    pre[y] = x;
    push_up(y);
    push_up(x);
}
void Splay(int r , int goal) {
    push_down(r);
    while(pre[r] != goal) {
        if(pre[pre[r]] == goal) {
            push_down(r);
            push_down(pre[r]);
            Rotate(r , ch[pre[r]][0] == r);
        }
        else  {
            push_down(r);
            push_down(pre[r]);
            push_down(pre[pre[r]]);
            int y = pre[r];
            int kind = (ch[pre[y]][0] == y);
            if(ch[y][kind] == y) {
                Rotate(r , !kind);
                Rotate(r , kind);
            }
            else {
                Rotate(y , kind);
                Rotate(r , kind);
            }
        }
    }
    push_up(r);
    if(goal == 0) root = r;
}//有新的操作之后注意稍微修改一下旋转操作
int get_Max(int r) {
    push_down(r);
    while(ch[r][1]) {
        r = ch[r][1];
        push_down(r);
    }
    push_up(r);
    return r;
}
void Remove() {
    if(!ch[root][0]) {
        root = ch[root][1];
        pre[root] = 0;
        push_up(root);
    }
    else {
        int Max_point = get_Max(ch[root][0]);
        Splay(Max_point , root);
        ch[Max_point][1] = ch[root][1];
        pre[ch[root][1]] = Max_point;
        root = Max_point;
        pre[root] = 0;
        push_up(root);
    }
}//新的remove操作删除节点。
void build(int l , int r , int &x , int fa) {
    if(l > r) return ;
    int mid = (l + r) >> 1;
    NewNode(x , fa , mid);
    build(l , mid - 1 , ch[x][0] , x);
    build(mid + 1 , r , ch[x][1] , x);
    push_up(x);
}
struct TnT {
    int pos , val;
}a[M << 1];
bool cmp(TnT x , TnT y) {
    if(x.val == y.val) return x.pos < y.pos;
    return x.val < y.val;
}
int main() {
    int n;
    while(scanf("%d" , &n) , n) {
        for(int i = 0 ; i < n ; i++) {
            scanf("%d" , &a[i].val);
            a[i].pos = i + 1;
        }
        sort(a , a + n , cmp);
        root = tot = 0;
        pre[root] = ch[root][1] = ch[root][0] = size[root] = rev[root] = 0;
        build(1 , n , root , 0);
        for(int i = 0 ; i < n - 1 ; i++) {
            Splay(a[i].pos , 0);
            Rev(ch[root][0]);
            printf("%d " , size[ch[root][0]] + i + 1);
            Remove();
        }
        printf("%d
" , n);
    }
    return 0;
}