Skip List — ordered dictionary with O(log n) expected search

using System;
using System.Collections.Generic;

public class SkipListNode<TK,TV> where TK : IComparable<TK> {
    public TK Key; public TV Val;
    public SkipListNode<TK,TV>[] Next;
    public SkipListNode(int level, TK k=default, TV v=default){ Key=k; Val=v; Next=new SkipListNode<TK,TV>[level]; }
}

public class SkipList<TK,TV> where TK : IComparable<TK> {
    readonly Random R = new(); readonly int MaxL; int Level;
    readonly SkipListNode<TK,TV> Head;
    public SkipList(int maxLevel=16){ MaxL=maxLevel; Level=1; Head=new SkipListNode<TK,TV>(MaxL); }

    int RandLevel(){ int l=1; while(l<MaxL && R.Next(2)==0) l++; return l; }

    public bool TryGet(TK key, out TV val){
        var x = Head;
        for (int i=Level-1;i>=0;i--)
            while (x.Next[i]!=null && x.Next[i].Key.CompareTo(key)<0) x=x.Next[i];
        x = x.Next[0];
        if (x!=null && x.Key.CompareTo(key)==0){ val=x.Val; return true; }
        val=default!; return false;
    }

    public void Insert(TK key, TV val){
        var update=new SkipListNode<TK,TV>[MaxL];
        var x=Head;
        for (int i=Level-1;i>=0;i--){
            while (x.Next[i]!=null && x.Next[i].Key.CompareTo(key)<0) x=x.Next[i];
            update[i]=x;
        }
        x=x.Next[0];
        if (x!=null && x.Key.CompareTo(key)==0){ x.Val=val; return; }
        int lvl=RandLevel(); if (lvl>Level){ for(int i=Level;i<lvl;i++) update[i]=Head; Level=lvl; }
        var n=new SkipListNode<TK,TV>(lvl, key, val);
        for (int i=0;i<lvl;i++){ n.Next[i]=update[i].Next[i]; update[i].Next[i]=n; }
    }
}