Splay hdu1890 Robotic Sort

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题意：一种排序，找到最小的，然后讲整段翻转，把数字提前。

思路：看到旋转就应该想到用splay。问题是怎么知道第几大的数字当前是第几个。

这里有种方法，就是记录每个数字的节点编号，然后只要把这个节点Splay到根节点，那么size[son[root][0]]就是数字所在的位置了。

有个需要注意的地方，就是翻转的时候，一定要这样写，不然会出各种问题，上一道Splay题都没注意到这些细节侥幸过了，诶。。

#include<map>#include<set>#include<cmath>#include<ctime>#include<stack>#include<queue>#include<cstdio>#include<cctype>#include<string>#include<vector>#include<cstring>#include<iomanip>#include<iostream>#include<algorithm>#include<functional>#define fuck(x) cout<<"["<<x<<"]"#define FIN freopen("input.txt","r",stdin)#define FOUT freopen("output.txt","w+",stdout)using namespace std;typedef long long LL;typedef pair<int, int>PII;const int MX = 1e5 + 5;const int mod = 1e9 + 7;const int INF = 0x3f3f3f3f;int size[MX], num[MX], col[MX], n;int son[MX][2], fa[MX], root, sz;struct Data{    int num,pos,id;    bool operator<(const Data &P) const{        if(num == P.num) return pos < P.pos;        return num < P.num;    }}A[MX];void Link(int x, int y, int c) {    fa[x] = y; son[y][c] = x;}void push_up(int rt) {    size[rt] = size[son[rt][0]] + size[son[rt][1]] + 1;}void Reverse(int rt){    col[rt] ^= 1;    swap(son[rt][0], son[rt][1]);}void push_down(int rt) {    if(col[rt]) {        Reverse(son[rt][0]);        Reverse(son[rt][1]);        col[rt] = 0;    }}void Rotate(int x, int c) {    int y = fa[x];    push_down(y); push_down(x);    Link(x, fa[y], son[fa[y]][1] == y);    Link(son[x][!c], y, c);    Link(y, x, !c);    push_up(y);}void Splay(int x, int g) {    push_down(x);    while(fa[x] != g) {        int y = fa[x], cx = son[y][1] == x, cy = son[fa[y]][1] == y;        if(fa[y] == g) Rotate(x, cx);        else {            if(cx == cy) Rotate(y, cy);            else Rotate(x, cx);            Rotate(x, cy);        }    }    push_up(x);    if(!g) root = x;}void NewNode(int f, int &rt) {    rt = ++sz;    fa[rt] = f, size[rt] = 1;    son[rt][0] = son[rt][1] = col[rt] = 0;}int Select(int k, int g) {    int rt = root;    while(size[son[rt][0]] != k) {        if(size[son[rt][0]] > k) rt = son[rt][0];        else k -= size[son[rt][0]] + 1, rt = son[rt][1];        push_down(rt);    }    Splay(rt, g);    return rt;}void Build(int l, int r, int &rt, int f) {    if(l > r) return;    int m = (l + r) >> 1, t;    NewNode(f, rt);    Build(l, m - 1, son[rt][0], rt);    scanf("%d", &num[rt]); A[m].pos = m;    A[m].num = num[rt]; A[m].id = rt;    Build(m + 1, r, son[rt][1], rt);    push_up(rt);}void Prepare(int n) {    sz = 0;    NewNode(0, root); num[1] = 0;    NewNode(root, son[root][1]); num[2] = 0;    Build(1, n, son[2][0], 2);    sort(A + 1, A + n + 1);    Splay(3, 0);}void Flip(int l, int r) {    Select(l - 1, 0);    Select(r + 1, root);    Reverse(son[son[root][1]][0]);}int main() {    //FIN;    while(~scanf("%d", &n), n) {        Prepare(n);        for(int i = 1; i <= n; i++) {            Splay(A[i].id, 0);            int p = size[son[root][0]];            Flip(i, p);            printf("%d%c", p, i == n ? '\n' : ' ');        }    }    return 0;}

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