SubStringWithUniqueCharacters

using System;
using System.Collections.Generic;
// To execute C#, please define "static void Main" on a class
// named Solution.

//Given a string s, that contains only 4 different characters ('A', 'B', 'C', 'D'), return the length of the smallest substring that contains at least one of all 4 unique charcters.

//"ACBAADBADCD" length = 4

//"C[ACCBD]BBAACCD" length = 5

// "AAA" -1
// Minimum Size of a Valid Substring = 4.
// Location Substring = Unk.
//  (n -4)
// ABBBACC]CADDD
class Solution
{
    static void Main(string[] args)
    {
        string input = "AAAAAAAAAAABBBCCCDDDAAAAA";
        Console.WriteLine(LengthOfValidSubString(input));
    }
    
    public static int LengthOfValidSubString(string s)
    {
     Dictionary<char, int> numberofChars = new Dictionary<char, int>() { 
         { 'A', 0 }, 
         { 'B', 0 },
         { 'C', 0 },
         { 'D', 0 } 
     };
     
     char[] inputArray = new char[s.Length];
     inputArray = s.ToCharArray();
     int pointer1 = 0;
     int pointer2 = 3;
     int windowSize = pointer2 - pointer1 +1;
     
    int bestSeen = Int32.MaxValue;
        
    for (var i = pointer1; i <= pointer2; i++)
    {
        numberofChars[inputArray[i]]++;
    }
        
    while (pointer2 < inputArray.Length - 1)
    {
        Console.WriteLine(pointer2 + " " + pointer1);
        if((windowSize == 4) && (!numberofChars.ContainsValue(0)))
        {
            return 4;
        }
        while ((windowSize > 4) && (numberofChars[inputArray[pointer1]] > 1))
        {
            numberofChars[inputArray[pointer1]]--;
            pointer1++;
            windowSize--;
        }
        
        while (numberofChars.ContainsValue(0))
        {
            pointer2++;
            numberofChars[inputArray[pointer2]]++;
            windowSize++;
        }
        bestSeen = Math.Min(bestSeen, windowSize);
        
    }
        
    if (bestSeen < Int32.MaxValue)
    {
        return bestSeen;
    }
    else
    {
        return -1;
    }
    
    
}
}