[BZOJ1552]robotic sort SPlay区间翻转

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SPlay区间翻转模板题

对于翻转区间[L,R]，将R+1旋转到根，L-1旋转到根节点的左儿子，此时L-1的右子树便是需要翻转的区间

打上标记即可

为了防止SPlay一个不存在的节点，可以在头尾加一个空节点（不加也行写起来蛋疼）

还不是很清楚SPlay(x)之前是否一定要access(x)，感觉一定要先下放标记再操作

改了好久最后要了数据才过，发现题目给的读入不是一个全排列

诶，细心看题啊

#include <cassert>#include <iostream>#include <cstdio>#include <algorithm> #define INF 1<<20#define N 500050 using namespace std; int siz[N],fa[N],rev[N],sta[N],s[N][2],a[N];int p[N],d[N],e[N],n,rt,cnt,tp; inline void update(int t) { siz[t] = siz[ s[t][0] ] + siz[ s[t][1] ] + 1; } void rotate(int t,int &k) {    int y = fa[t] , z = fa[y] , l = (s[y][0] == t)^1 , r = l ^ 1;    if (y == k) k = t; else {        if (s[z][0] == y) s[z][0] = t; else s[z][1] = t;    }    s[y][l] = s[t][r]; s[t][r] = y;    fa[t] = z , fa[y] = t , fa[ s[y][l] ] = y;    update(y); update(t);} inline void push_down(int t) {    if (!rev[t]) return ;    swap(s[t][0],s[t][1]);    rev[ s[t][0] ] ^= 1; rev[ s[t][1] ] ^= 1; rev[t] = 0;} inline void access(int t,int d) {    while (t!=d && t!=rt) { sta[++tp] = t; t = fa[t]; } sta[++tp] = d;    while (tp) { push_down(sta[tp]); tp--; }} void SPlay(int t,int &d) {    access(t,d);    while (t != d) {        int y = fa[t] , z = fa[y];        if (y != d) {            if ((s[y][0] == t) ^ (s[z][0] == y)) rotate(t,d); else rotate(y,d); }        rotate(t,d);    }} void build(int l,int r,int &t,int f) {    int mid = (l + r) >> 1;    t = ++cnt;    fa[t] = f;    siz[t] = 1;    if (p[mid] != INF) d[ p[mid] ] = t;    if (l == r) return ;    if (l <= mid-1) build(l,mid-1,s[t][0],t);    if (mid+1 <= r) build(mid+1,r,s[t][1],t);    siz[t] = siz[ s[t][0] ] + siz[ s[t][1] ] + 1;} int kth(int k,int t) {    push_down(t); int tmp = siz[ s[t][0] ] + 1;    if (tmp == k) return t;    return tmp > k ? kth(k,s[t][0]) : kth(k-tmp,s[t][1]);}int rever(int L,int R) {int u,v;v = kth(R,rt); SPlay(v,rt);if (s[v][0] == 0) {while(1);}u = kth(L,rt); SPlay(u,s[v][0]); return rev[ s[u][1] ] ^= 1;}bool cmp(int p1,int p2) {return a[p1] == a[p2] ? p1 < p2 : a[p1] < a[p2];} int main(){#ifndef ONLINE_JUDGEfreopen("sort.in","r",stdin);freopen("sort.out","w",stdout);#endif    scanf("%d",&n);    for (int i=1;i<=n;i++) scanf("%d",&a[i]) , e[i] = i;    sort(e+1,e+n+1,cmp);    for (int i=1;i<=n;i++) a[ e[i] ] = a[ e[i-1] ] + 1;    for (int i=2;i<=n+1;i++) p[i] = a[i-1];        p[1] = p[n+2] = INF;    build(1,n+2,rt,0);    for (int i=2;i<=n+1;i++) {        SPlay(d[i-1],rt);        int ans = siz[ s[rt][0] ] + 1;        printf("%d%c",ans-1,i==n+1?'\n':' ');        rever(i-1,ans+1);    }    return 0;}

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