Basic merge
Input
a = [1, 3, 5], b = [2, 4, 6]
Output
[1, 2, 3, 4, 5, 6]
Alternate elements from the two arrays in sorted order.
Full lesson preview
Merge Two Sorted Arrays with Two Pointers
Merge two sorted lists into a single sorted list using the two-pointer technique.
Python practice8 minArrays – Fundamentals & PatternsBeginnerLast updated March 25, 2026
Problem statement
Given two sorted arrays (ascending order), return a new array that contains all elements from both input arrays in sorted order. Do not use built-in sort on the combined array; instead, take advantage of the fact that the two inputs are already sorted and merge them in O(n+m) time and O(n+m) additional space.
Task
Implement an efficient merge of two sorted arrays that returns a new sorted array containing all elements from both inputs.
Examples
Input format
Two lists of integers: merge_sorted_arrays(a, b).
Output format
A single list of integers sorted in ascending order.
Constraints
0 <= len(a), len(b) <= 10^5. Values can be negative, zero, or positive. Aim for O(n + m) time and O(n + m) space.
Samples
Sample 1
Input
merge_sorted_arrays([1,2], [3,4])
Output
[1, 2, 3, 4]
Simple concatenation in order using merge.