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Coding & Algorithms questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master coding & algorithms interviews.

What difficulty level is this interview question?

This is a easy difficulty Coding & Algorithms question, commonly asked during Onsite rounds at Walmart Labs.

What role is this question designed for?

This question is commonly asked for Software Engineer candidates at Walmart Labs during technical interviews.

Merge two sorted arrays in-place | Walmart Labs Interview Question

Quick Overview

This question evaluates proficiency in array manipulation, in-place merging concepts, and understanding of time and space complexity when combining sorted sequences. Commonly asked in the coding and algorithms domain (arrays/sorting), it tests practical implementation skills and the ability to produce efficient, low-memory solutions while handling ordering constraints and edge cases.

You are given two integer arrays sorted in non-decreasing order, and two integers m and n:

nums1 has length m + n . The first m elements of nums1 contain valid numbers in sorted order. The last n elements of nums1 are placeholders (you can assume they are set to any values and should be ignored).
nums2 has length n , and all n elements are valid and sorted in non-decreasing order.

Write an algorithm that merges the elements of nums2 into nums1 so that nums1 becomes a single sorted array containing all m + n elements, in-place (i.e., without using an additional array of size m + n).

Return value is not required; modify nums1 directly.

Example

Input:

nums1 = [1, 3, 5, 0, 0, 0] , m = 3
nums2 = [2, 4, 6] , n = 3

After calling your function, nums1 should become:

nums1 = [1, 2, 3, 4, 5, 6]

Constraints

0 <= m, n <= 10^5
len(nums1) = m + n
len(nums2) = n
Arrays are already sorted in non-decreasing order.

Describe the algorithm and then implement it in the language of the interviewer's choice.

Merge two sorted arrays in-place

Quick Overview