Algorithm for two languages that merges and sorts two arrays without mutating one

Question

This algorithm, which I have included its flowchart as well, takes an array of A[n], which is unsorted and unmutatable and an array of B[k], which is sorted and includes n zeroes and then merges, and sorts them together. The entire code in Python and C# can be found here and on this very post.

In C#:

class Program
{
    static void Main(string[] args)
    {
        var inputA = Console.ReadLine();
        var inputB = Console.ReadLine();

        char[] delimiter = { ' ', ',', '-' };
        string[] inputASplit = inputA.Split(delimiter, StringSplitOptions.RemoveEmptyEntries);
        string[] inputBSplit = inputB.Split(delimiter, StringSplitOptions.RemoveEmptyEntries);

        int[] listA = new int[inputASplit.Length];
        int[] listB = new int[inputBSplit.Length];

        for (int i = 0; i < inputASplit.Length; i++)
        {
            listA[i] = int.Parse(inputASplit[i]);
        }

        for (int i = 0; i < inputBSplit.Length; i++)
        {
            listB[i] = int.Parse(inputBSplit[i]);
        }

        int[] concatinatedList = MergeSort(listA, listB);

        foreach (var number in concatinatedList)
        {
            Console.WriteLine(number);
        }

        Console.ReadKey();
    }

    static int[] ParseListA(int[] ListA)
    {
        List<int> newListA = ListA.ToList();
        newListA.Sort();

        return newListA.ToArray();

    }

    static int CountZeros(int[] ListB)
    {
        int zeroCount = 0;

        for (int i = 0; i < ListB.Length; i++)
        {
            if (ListB[i] == 0)
            {
                zeroCount += 1;
            }
        }

        if (zeroCount == 0)
        {
            throw new Exception("List B doesn't contain any Zeroes.");
        }

        return zeroCount;
    }

    static int[] MergeSort(int[] listA, int[] listB)
    {
        int[] newListA = ParseListA(listA);
        int zeroCount = CountZeros(listB);
        int[] newListB = new int[listB.Length - zeroCount];

        if (newListA.Length != zeroCount)
        {
            throw new Exception("There weren't enough buffers!");
        } 

        for (int i = 0; i < listB.Length; i++)
        {
            if (listB[i] != 0)
            {
                for (int j = 0; j < newListB.Length; j++)
                {
                    newListB[j] = listB[i];
                }
            }
        }

        int[] concatenatedList = newListA.Concat(newListB).ToArray();
        Array.Sort(concatenatedList);

        return concatenatedList;
    }

In Python:

def ParseListA(listA):
    newListA = sorted(listA);

    return newListA;


def MergeSort(listA, listB):
    newListA = ParseListA(listA);    
    zeroCount = 0;

    for number in listB:
        if number == 0:
            zeroCount += 1;

    if zeroCount == 0:
        raise ValueError("Needs zeros!");
        return;

    newlistB = [i for i in listB if i != 0];


    return sorted(newListA+newlistB);

def Main():
    listAInput = input("Enter List A: ").split(' ');
    listBInput = input("Enter List B: ").split(' ');

    listA = [int(i) for i in listAInput];
    listB = [int(i) for i in listBInput];

    print(MergeSort(listA, listB));

Main()

Answer 1

1. Python doesn't use semicolons at the end of a line.
2. The function ParseListA does nothing that the built-in function sorted doesn't do already. Remove it.

3. In MergeSort, you can use the built-in function any to make sure you have at least one zero in ListB, like this:

   if not any(i==0 for i in listB):
       raise ValueError("Needs zeros")
   

   These two lines replace all the code beginning with zeroCount=0 and ending with return;. The return statement is, incidentally, unreachable code since it follows a raise statement.

4. At the end of MergeSort, you concatenate the two lists and then sort them. If you are going to do that, the initial sort of listA is redundant.

When all is said and done, the function ParseListA is gone and MergeSort is only four lines long. Only one sort operation is required:

def MergeSort(listA, listB):
    if not any(i==0 for i in listB):
        raise ValueError("Needs zeros")
    newB = [i for i in listB if i != 0]
    return sorted(listA + newB)