Question2.cs

using System;
using System.Collections.Generic;
using System.Linq;

namespace Homework4
{
    public static class Question2
    {
        public static void Run()
        {
            for (int numerator = 10; numerator < 100; numerator++)
            {
                for (int denominator = 10; denominator < 100; denominator++)
                {
                    if (IsFreakDivisible(numerator, denominator))
                    {
                        Console.WriteLine($"{numerator}/{denominator}");
                    }
                }
            }
        }

        public static bool IsFreakDivisible(int numerator, int denominator)
        {
            if (numerator < 10 || numerator > 99)
            {
                return false;
            }
            
            if (denominator < 10 || denominator > 99)
            {
                return false;
            }
            
            if (numerator % 10 == 0 || denominator % 10 == 0)
            {
                return false;
            }
            
            if (denominator <= numerator)
            {
                return false;
            }

            int[] numeratorDigits = GetDigits(numerator);
            if (!IsAllDifferent(numeratorDigits))
            {
                return false;
            }
            
            int[] denominatorDigits = GetDigits(denominator);
            if (!IsAllDifferent(denominatorDigits))
            {
                return false;
            }

            int intersection = GetIntersection(numeratorDigits, denominatorDigits);
            if (intersection < 0)
            {
                return false;
            }

            int newNumerator = ConvertToDecimal(Remove(numeratorDigits, intersection));
            int newDenominator = ConvertToDecimal(Remove(denominatorDigits, intersection));

            if (newDenominator == 0)
            {
                return false;
            }
            
            return (double)numerator / denominator == (double)newNumerator / newDenominator;
        }

        private static int ConvertToDecimal(int[] digits)
        {
            int result = 0;
            for (int i = 0; i < digits.Length; i++)
            {
                result += digits[i] * (int)Math.Pow(10, i);
            }

            return result;
        }
        
        private static int[] GetDigits(int number)
        {
            if (number < 0)
            {
                number = Math.Abs(number);
            }

            List<int> digits = new List<int>();
            
            while (number >= 10)
            {
                int digit = number % 10;
                number = (number - digit) / 10;
                
                digits.Add(digit);
            }
            
            digits.Add(number);

            return digits.ToArray();
        }

        private static bool IsAllDifferent(int[] digits)
        {
            for (int i = 0; i < digits.Length; i++)
            {
                if (digits.Count(x => x == digits[i]) > 1)
                {
                    return false;
                }
            }

            return true;
        }

        private static int GetIntersection(int[] digits1, int[] digits2)
        {
            for (int i = 0; i < digits1.Length; i++)
            {
                if (digits2.Contains(digits1[i]))
                {
                    return digits1[i];
                }
            }

            return -1;
        }

        private static T[] Remove<T>(T[] digits, T number)
        {
            List<T> list = new List<T>(digits);
            list.Remove(number);
            return list.ToArray();
        }
        
    }
}