FHQ-Treap

要啥splay?

【模板】文艺平衡树：https://www.luogu.org/problem/P3391

FHQ维护区间，每次将区间拆成[1,l-1],[l,r],[r+1,n]，然后把[l,r]打上标记即可

最后中序遍历

#define B cout << "breakpoint" << endl; 
#define O(x) cout << #x << " " << x << endl;
#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
#include<queue>
#include<cstdlib>
using namespace std;
inline int read()
{
    int ans = 0,op = 1;
    char ch = getchar();
    while(ch < '0' || ch > '9')
    {
        if(ch == '-') op = -1;
        ch = getchar();
    }
    while(ch >= '0' && ch <= '9')
    {
        (ans *= 10) += ch - '0';
         ch = getchar();
    }
    return ans * op;
}
const int maxn = 1e5 + 5;
#define ls ch[now][0]
#define rs ch[now][1]
int ch[maxn][2],sz[maxn],val[maxn],key[maxn],tag[maxn],tot,rt;
inline int New(int k) { key[++tot] = rand(),val[tot] = k,sz[tot] = 1; return tot; }
inline int up(int now) { return sz[now] = sz[ls] + sz[rs] + 1; }
inline void down(int now)
{
    if(!tag[now]) return;
    swap(ls,rs);
    tag[ls] ^= 1,tag[rs] ^= 1;
    tag[now] = 0;
}
void split(int now,int k,int &x,int &y)//x < k,y > k
{
    if(!now) { x = y = 0; return; }
    down(now); 
    if(sz[ls] < k) x = now,split(rs,k - sz[ls] - 1,rs,y);
    else y = now,split(ls,k,x,ls);
    up(now);
}
int merge(int x,int y)//小根堆,x <= y 
{
    if(!x || !y) return x + y;

    if(key[x] < key[y])
    {
        down(x); 
        ch[x][1] = merge(ch[x][1],y);
        up(x);
        return x;
    }
    else
    {    
        down(y);
        ch[y][0] = merge(x,ch[y][0]);
        up(y);
        return y;
    }
}
void solve(int now)
{
    if(!now) return;
    down(now);
    solve(ls);
    printf("%d ",val[now]);
    solve(rs);
}
int main()
{
    int n = read(),m = read();
    for(int i = 1;i <= n;i++)
        rt =  merge(rt,New(i));
    for(int i = 1;i <= m;i++)
    {
        int l = read(),r = read();
        int x,y,z;
        split(rt,l - 1,x,y);
        split(y,r - l + 1,y,z);
        tag[y] ^= 1;
        rt = merge(x,merge(y,z));
    }
    solve(rt);
}