[Cerc2007]robotic sort

splay区间反转练手题

#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;
const int N=100005;
int n,fa[N],ch[N][2],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][0]]+siz[ch[x][1]]+1;}
void pushdown(int x) {
    if(rev[x]) {
        swap(ch[x][0],ch[x][1]);
        rev[ch[x][0]]^=1,rev[ch[x][1]]^=1;
        rev[x]=0;
    }
}
int build(int f,int l,int r) {
    if(l>r) return 0;
    int now=++tot,mid=l+r>>1;
    val[now]=a[mid].v;fa[now]=f;
    pos[a[mid].v]=now;
    ch[now][0]=build(now,l,mid-1);
    ch[now][1]=build(now,mid+1,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]][1]==x;
    ch[f][tag]=ch[x][tag^1];
    fa[ch[f][tag]]=f;
    fa[f]=x;
    ch[x][tag^1]=f;
    fa[x]=ff;
    if(ff) ch[ff][f==ch[ff][1]]=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]][0])==(f==ch[fa[f]][0])?f:x);
    if(!tar) rt=x;
}
int nxt(){
    pushdown(rt);
    int x=ch[rt][1];
    while(pushdown(x),ch[x][0]) x=ch[x][0];
    return x;
}
int main() {
    scanf("%d",&n);
    for(int i=1;i<=n;i++) scanf("%d",&a[i+1].v),a[i+1].id=i+1;
    a[1].v=0;a[n+2].v=n+1;//a[1].id=1,a[n+2].id=n+2;
    sort(a+2,a+2+n,cmp1);
    for(int i=2;i<=n+1;i++) a[i].v=i-1;
    sort(a+2,a+2+n,cmp2);
    rt=build(0,1,n+2);
    for(int i=1;i<=n;i++) {
        int x=pos[i];splay(x,0);
        printf("%d ",siz[ch[x][0]]);        
        x=nxt();
        int y=pos[i-1];
        splay(y,0);
        splay(x,y);
        rev[ch[x][0]]^=1;
    }
}

robotic sort