codilityChallenge.cs

using System;
using System.Collections.Generic;

class Solution
{
    public int solution(int[] A)
    {
        var numberOfVariations = 0;
        var alreadyCut = false;

        for (int i = 0; i + 2 < A.Length; i++)
        {
            var firstHeight = A[i];
            var secondHeight = A[i + 1];
            var thirdHeight = A[i + 2];

            var gradient1 = firstHeight.CompareTo(secondHeight);
            var gradient2 = secondHeight.CompareTo(thirdHeight);

            if (gradient1 == 0)
            {
                if (alreadyCut)
                {
                    return -1;
                }
                alreadyCut = true;

                numberOfVariations += 2;
            }

            if (gradient2 == 0)
            {
                if (alreadyCut)
                {
                    return -1;
                }
                alreadyCut = true;

                numberOfVariations += 2;
            }

            if (gradient1 == gradient2)
            {
                if (alreadyCut)
                {
                    return -1;
                }

                alreadyCut = true;

                var isRestOfArrayAestheticallyPleasing = IsAestheticallyPleasing(A, i + 4);

                int? fourthHeight = null;

                //if fourth not exists
                if (i + 3 < A.Length)
                {
                    fourthHeight = A[i + 3];

                    //cut third tree and find if possible
                    bool isThirdTreeCutSuitsTheRule = IsAestheticallyPleasing(firstHeight, secondHeight, fourthHeight);
                    if (isRestOfArrayAestheticallyPleasing & isThirdTreeCutSuitsTheRule)
                    {
                        numberOfVariations++;
                    }
                }

                //cut first tree and find if possible
                bool isFirstTreeCutSuitsTheRule = IsAestheticallyPleasing(secondHeight, thirdHeight, fourthHeight);

                //cut second tree and find if possible
                bool isSecondTreeCutSuitsTheRule = IsAestheticallyPleasing(firstHeight, thirdHeight, fourthHeight);

                if (isRestOfArrayAestheticallyPleasing & isFirstTreeCutSuitsTheRule)
                {
                    numberOfVariations++;
                }
                if (isRestOfArrayAestheticallyPleasing & isSecondTreeCutSuitsTheRule)
                {
                    numberOfVariations++;
                }
            }
        }

        return numberOfVariations;
    }

    private bool IsAestheticallyPleasing(int firstHeight, int secondHeight)
    {
        var gradient = firstHeight.CompareTo(secondHeight);

        if (gradient != 0)
        {
            return true;
        }

        return false;
    }

    private bool IsAestheticallyPleasing(int firstHeight, int secondHeight, int? thirdHeight)
    {
        if (thirdHeight.HasValue == false)
        {
            return IsAestheticallyPleasing(firstHeight, secondHeight);
        }

        var gradient1 = firstHeight.CompareTo(secondHeight);
        var gradient2 = secondHeight.CompareTo(thirdHeight);

        if (gradient1 != gradient2 && gradient1 != 0 && gradient2 != 0)
        {
            return true;
        }

        return false;
    }


    private bool IsAestheticallyPleasing(int[] arr, int indexToStart)
    {
        for (int i = indexToStart; i + 2 < arr.Length; i++)
        {
            var firstHeight = arr[i];
            var secondHeight = arr[i + 1];
            var thirdHeight = arr[i + 2];

            if (!IsAestheticallyPleasing(firstHeight, secondHeight, thirdHeight))
            {
                return false;
            }
        }

        return true;
    }
}