Splay 模板

模板题：https://www.luogu.org/problemnew/show/P3391

---

#include<bits/stdc++.h>
using namespace std;
const int N=100005;
int ch[N][2],par[N],val[N],cnt[N],size[N],rev[N],root,ncnt;
int n,m,x,y;
bool chk(int x){
    return ch[par[x]][1]==x;
}
void pushup(int x){
    size[x]=size[ch[x][0]]+size[ch[x][1]]+cnt[x];
}
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;
    }
}
void rotate(int x){//将x旋转到x的父节点上 
    int y=par[x],z=par[y],k=chk(x),w=ch[x][k^1];
    ch[y][k]=w,par[w]=y;
    ch[z][chk(y)]=x,par[x]=z;
    ch[x][k^1]=y,par[y]=x;
    pushup(y),pushup(x);
}
void splay(int x,int goal=0){
    while(par[x]!=goal){
        int y=par[x],z=par[y];
        if(z!=goal){
            if(chk(x)==chk(y))rotate(y);
            else rotate(x);
        }
        rotate(x);
    }
    if(!goal)root=x;
}
void insert(int x){
    int cur=root,p=0;
    while(cur&&val[cur]!=x){
        p=cur;
        cur=ch[cur][x>val[cur]];
    }
    if(cur){
        cnt[cur]++;
    }else{
        cur=++ncnt;
        if(p)ch[p][x>val[p]]=cur;
        ch[cur][0]=ch[cur][1]=0;
        par[cur]=p,val[cur]=x;
        cnt[cur]=size[cur]=1;
    }
    splay(cur);
}
void find(int x){
    int cur=root;
    while(ch[cur][x>val[cur]]&&val[cur]!=x){
        cur=ch[cur][x>val[cur]];
    }
    splay(cur);
}
int kth(int k){
    int cur=root;
    while(1){
        pushdown(cur);
        if(ch[cur][0]&&k<=size[ch[cur][0]]){
            cur=ch[cur][0];
        }else if(k>size[ch[cur][0]]+cnt[cur]){
            k-=size[ch[cur][0]]+cnt[cur];
            cur=ch[cur][1];
        }else{
            return cur;
        }
    }
}
void reverse(int l,int r){
    int x=kth(l),y=kth(r+2);
    splay(x),splay(y,x);
    rev[ch[y][0]]^=1;
}
int pre(int x){
    find(x);
    if(val[root]<x)return root;
    int cur=ch[root][0];
    while(ch[cur][1])cur=ch[cur][1];
    return cur;
}
int succ(int x){
    find(x);
    if(val[root]>x)return root;
    int cur=ch[root][1];
    while(ch[cur][0])cur=ch[cur][0];
    return cur;
}
void output(int x){
    pushdown(x);
    if(ch[x][0])output(ch[x][0]);
    if(val[x]&&val[x]<=n)printf("%d ",val[x]);
    if(ch[x][1])output(ch[x][1]);
}
int main(){
    scanf("%d%d",&n,&m);
    for(int i=0;i<=n+1;i++)insert(i);
    while(m--){
        scanf("%d%d",&x,&y);
        reverse(x,y);
    }
    output(root);
}