Merge Sorted Arrays: LeetCode Submission has different output than LeetCode Playground and Visual Studio [C#]

Question

Trying to attempt to solve 88. Merge Sorted Array with C# using a for and a while loop. Leetcode instructs to save the correct output in [nums1] array instead of a return output. These are the assumptions and inputs for the merge sorted array.

1. Prompt:

2. My Code:

public void Merge(int[] nums1, int m, int[] nums2, int n) {
        if (m == 0)
        {
            Console.WriteLine("Num 1 Before: {0}", nums1[0]);
            nums1 = (int[])nums2.Clone();
            Console.WriteLine("Num 1 After: {0}", nums1[0]);
        }
        
        else if ( n != 0 )
        {
            int arrTwoIt = 0;
            for ( int i = m; i <m+n; i++)
            {
                nums1[i] = nums2[arrTwoIt++];
            }
            
            int arrOneIt = 0;
            arrTwoIt = m;
            while (arrOneIt < m)
            {
                if (nums1[arrOneIt] > nums1[arrTwoIt])
                {
                    int leftItemTemp = nums1[arrOneIt];
                    nums1[arrOneIt] = nums1[arrTwoIt];
                    nums1[arrTwoIt++] = leftItemTemp;
                }
                
                arrOneIt++;
            }
        }
    }

3. Input: {0}, 0, {1} , 1
4. Output: LeetCode Playground:

5. Output: Visual Studios:

6. LeetCode Submission Output:

I am not sure where to go from there. Im not sure what I am missing. Any help is appreciated.

Answer 1

Try this simple 3 pointer approach:

namespace CodingInterview;

public static class LeetCodeQuestions
{
    // Question: https://leetcode.com/problems/merge-sorted-array/?envType=study-plan-v2&envId=top-interview-150
    // Time complexity: O(m+n) because we're looping backwards through m+n elements
    // Space complexity: O(1) - Constant because we're not creating any new data structures that scale with input size
    public static void MergeSortedArrays(int[] nums1, int m, int[] nums2, int n) {
        // 3 pointer approach
        var i = m - 1;
        var j = n - 1;
        var k = m + n - 1;

        // Loop from k to 0
        while (k > -1){
            // Means we sorted all of nums1, but we still have to place nums2 elements
            if(i < 0){
                nums1[k] = nums2[j];
                j--;
            }
            // Means we sorted all of nums2, but there are elements in nums1 but they're already sorted, so you can just get out
            else if (j < 0){
                break;
            }
            else if (nums1[i] > nums2[j]){
                nums1[k] = nums1[i];
                i--;
            }
            else{
                nums1[k] = nums2[j];
                j--;
            }
            k--;
        }
    }
}

Test it. I'm using xUnit.

namespace CodingInterview.Tests;

public class LeetCodeQuestionsTests
{
    [Theory]
    // Test Cases 1-3
    [InlineData(new[] {1, 2, 3, 0, 0, 0}, 3, new[] {2, 5, 6}, 3, new[] {1, 2, 2, 3, 5, 6})]
    [InlineData(new[] {1}, 1, new int[] {}, 0, new[] {1})]
    [InlineData(new[] {0}, 0, new[] {1}, 1, new[] {1})]
    public void Merge_Sorted_Arrays(int[] nums1, int m, int[] nums2, int n, int[] expected)
    {
        // Act
        LeetCodeQuestions.MergeSortedArrays(nums1, m, nums2, n);
        
        // Assert
        Assert.Equal(expected, nums1);
    }
}

Answer 2

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Console1.Core.Algorithms
{

    class Merge_Sorted_Array
    {


        static void Main(string[] args)
        {
            int[] nums1 = { 1, 2, 3, 0, 0, 0 }; //here you can put your values
            int[] nums2 = { 2, 5, 6 }; //here you can put your values

            int count = 0;

            for (int i = 0; i < nums1.Length; i++)
            {
                count++;
            }

            for (int i = 0; i < nums2.Length; i++)
            {
                count++;
            }

            int[] nums3 = new int[count];
            for (int i = 0; i < nums1.Length; i++)
            {
                nums3[i] = nums1[i];
            }
            int d = nums1.Length;
            for (int i = 0; i < nums2.Length; i++)
            {
                nums3[d] = nums2[i];
                d++;
            }


            List<int> arrayList =  new List<int>();

            for (int i = 0; i < nums3.Length; i++)
            { 
                if (nums3.ElementAt(i).Equals(0))
                {
                    continue;
                }
                else
                {
                    arrayList.Add(nums3.ElementAt(i));
                }
            }

            arrayList.Sort();

            int[] ans = new int[arrayList.Count];

            for (int i = 0; i < arrayList.Count; i++)
            {
                ans[i] = arrayList.ElementAt(i);
            }

            for (int i = 0; i < ans.Length; i++)
            {
                Console.WriteLine(ans.ElementAt(i));
            }
        }
    }
}

Answer 3

You can merge two arrays first & Simply call Array.Sort() method. If you don't want to use any in-Built method, you can sort with your custom logic.

public void Merge(int[] nums1, int m, int[] nums2, int n) {
    
    for(int i = 0; i < nums2.Length; i++){
        
        nums1[i + m] = nums2[i];
        
    }
    Array.Sort(nums1);
}