Задача: наибольшая подстрока между двумя одинаковыми символами

FindMaxLengthBetweenEqualCharacters.cs

using System;
using System.Collections.Generic;
					
public class Program
{
	public static int FindMaxLengthBetweenEqualCharacters(string s) {
		int maxLen = -1;
		var map = new Dictionary<char, int>();
		for (int i = 0; i < s.Length; i++)
		{
		    if (!map.ContainsKey(s[i]))
		    {
			map[s[i]] = i;
		    }
		    else 
		    {
			maxLen = Math.Max(maxLen, i - map[s[i]] - 1);
		    }
		}

		return maxLen;
	}
	
	public static void Main()
	{
		Console.WriteLine("UniLecs");
		
		// tests
		Console.WriteLine(FindMaxLengthBetweenEqualCharacters("abca").ToString()); // 2
		Console.WriteLine(FindMaxLengthBetweenEqualCharacters("abcaefghqwrta").ToString()); // 11
	}
}