fhq treap 封装

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define ls (l[cnt])
#define rs (r[cnt])
const int N = 100005;

struct Ftree
{
	int l[N], r[N], val[N], rad[N], siz[N], ecnt, rt;
	int New(int k)
	{
		val[++ecnt] = k;
		rad[ecnt] = rand();
		siz[ecnt] = 1;
		return ecnt;
	}
	void update(int cnt)
	{
		siz[cnt] = siz[ls] + siz[rs] + 1;
	}
	void split(int cnt, int k, int &x, int &y)
	{
		if(cnt == 0)
		{
			x = y = 0;
			return ;
		}
		if(val[cnt] <= k)
		{
			x = cnt;
			split(rs, k, rs, y);
		}
		if(val[cnt] > k)
		{
			y = cnt;
			split(ls, k, x, ls);
		}
		update(cnt);
	} 
	int merge(int x, int y)
	{
		if(x == 0) return y;
		if(y == 0) return x;
		if(rad[x] <= rad[y])
		{
			r[x] = merge(r[x], y);
			update(x);
			return x;
		}
		if(rad[x] > rad[y])
		{
			l[y] = merge(x, l[y]);
			update(y);
			return y;
		}
	}
	int kth(int cnt, int k)
	{
		if(siz[ls] + 1 == k) return val[cnt];
		if(siz[ls] >= k) return kth(ls, k);
		else return kth(rs, k - siz[ls] - 1);
	}
	void add(int k)
	{
		int x, y;
		split(rt, k, x, y);
		rt = merge(merge(x, New(k)), y);
	}
	void del(int k)
	{
		int x, y, z;
		split(rt, k, x, y);
		split(x, k - 1, x, z);
		z = merge(l[z], r[z]);
		rt = merge(merge(x, z), y);
	}
	int suc(int k)
	{
		int x, y, ans; 
		split(rt, k, x, y);
		ans = kth(y, 1);
		rt = merge(x, y);
		return ans;
	}
	int pre(int k)
	{
		int x, y, ans;
		split(rt, k - 1, x, y);
		ans = kth(x, siz[x]);
		rt = merge(x, y);
		return ans;
	}	
}ft;
int main()
{
	
}

fhq treap 封装

原文：https://www.cnblogs.com/lcezych/p/13236342.html