[Cerc2007]robotic sort

splay区间反转练手题

#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;
const int N=;
int n,fa[N],ch[N][],val[N],siz[N],tot,pos[N],rt;
struct Node{
    int id,v;
}a[N];
bool cmp1(Node x,Node y) {return x.v==y.v?x.id<y.id:x.v<y.v;}
bool cmp2(Node x,Node y) {return x.id<y.id;}
bool rev[N];
inline void pushup(int x) {siz[x]=siz[ch[x][]]+siz[ch[x][]]+;}
void pushdown(int x) {
    if(rev[x]) {
        swap(ch[x][],ch[x][]);
        rev[ch[x][]]^=,rev[ch[x][]]^=;
        rev[x]=;
    }
}
int build(int f,int l,int r) {
    if(l>r) return ;
    int now=++tot,mid=l+r>>;
    val[now]=a[mid].v;fa[now]=f;
    pos[a[mid].v]=now;
    ch[now][]=build(now,l,mid-);
    ch[now][]=build(now,mid+,r);
    pushup(now);
    return now;
}
inline void rotate(int x) {
    int f=fa[x],ff=fa[f];
    pushdown(f);pushdown(x);
    bool tag=ch[fa[x]][]==x;
    ch[f][tag]=ch[x][tag^];
    fa[ch[f][tag]]=f;
    fa[f]=x;
    ch[x][tag^]=f;
    fa[x]=ff;
    if(ff) ch[ff][f==ch[ff][]]=x;
    pushup(f);pushup(x);
}
inline void splay(int x,int tar){
    for(int f;(f=fa[x])!=tar;rotate(x)) if(fa[f]!=tar)rotate((x==ch[fa[x]][])==(f==ch[fa[f]][])?f:x);
    if(!tar) rt=x;
}
int nxt(){
    pushdown(rt);
    int x=ch[rt][];
    while(pushdown(x),ch[x][]) x=ch[x][];
    return x;
}
int main() {
    scanf("%d",&n);
    for(int i=;i<=n;i++) scanf("%d",&a[i+].v),a[i+].id=i+;
    a[].v=;a[n+].v=n+;//a[1].id=1,a[n+2].id=n+2;
    sort(a+,a++n,cmp1);
    for(int i=;i<=n+;i++) a[i].v=i-;
    sort(a+,a++n,cmp2);
    rt=build(,,n+);
    for(int i=;i<=n;i++) {
        int x=pos[i];splay(x,);
        printf("%d ",siz[ch[x][]]);
        x=nxt();
        int y=pos[i-];
        splay(y,);
        splay(x,y);
        rev[ch[x][]]^=;
    }
}

robotic sort