Merge Sort Algorithm — DSA Technical Interview Questions & Answers

Merge Sort Algorithm

Merge Sort Algorithm

  • Merge Sort Algorithm is a DSA topic. In plain words you use it for names A→Z in the roll list. Don’t start with a slogan — start with that picture.
  • Smallest example: n log n vs n². Type it, run it, and say what you see. If you can do that from memory, you know Merge Sort Algorithm.
  • From the example next to this theory: Merge Sort Algorithm — merge sort divides the array, sorts halves, then merges — O(n log n).
  • Trap: unstable sort when equal keys matter. Fix that before you talk about advanced DSA.
  • Viva: what is Merge Sort Algorithm? Then show n log n vs n². Then name the trap.

Technical Interview Tip: What is Merge Sort Algorithm? Show this: n log n vs n². Trap: unstable sort when equal keys matter.

Code Examples for Merge Sort Algorithm

Merge Sort Algorithm — working example

def merge_sort(arr):
    if len(arr) <= 1:
        return arr
    mid = len(arr) // 2
    left = merge_sort(arr[:mid])
    right = merge_sort(arr[mid:])
    out, i, j = [], 0, 0
    while i < len(left) and j < len(right):
        if left[i] <= right[j]:
            out.append(left[i]); i += 1
        else:
            out.append(right[j]); j += 1
    return out + left[i:] + right[j:]

print(merge_sort([5, 1, 4, 2]))

Merge Sort Algorithm — merge sort divides the array, sorts halves, then merges — O(n log n).

How to Explain Merge Sort Algorithm to an Interviewer

What is Merge Sort Algorithm?

Used for names A→Z the roll list Not just the heading

Give one small example of Merge Sort Algorithm.

n log n vs n² Merge Sort Algorithm — merge sort divides the array, sorts halves, then merges — O(n log n)

What mistake do beginners make with Merge Sort Algorithm?

unstable sort when equal keys matter Show the fix

Where do you use Merge Sort Algorithm?

the roll list names A→Z