What is the best way to find the middle of three numbers?

Analytical
Easy
Infosys
143.3K views

This problem requires determining the median value among three distinct integers without sorting them fully. It tests logical reasoning and conditional branching efficiency.

Why Interviewers Ask This

Interviewers use this to gauge a candidate's logical deduction skills and ability to minimize computational steps. They want to see if the candidate can solve the problem using fewer comparisons than a full sort. It also checks for clarity in handling multiple conditional branches and avoiding redundant checks.

How to Answer This Question

Explain that sorting three numbers takes more operations than necessary. Propose a series of if-else statements that compare pairs to identify the middle value directly. Discuss how many comparisons are needed (typically 3) and why this is optimal. Walk through specific examples to show how the logic handles different orderings of the three numbers.

Key Points to Cover

  • Direct comparison logic
  • Avoiding full sort
  • Minimal comparisons
  • Logical branching

Sample Answer

To find the middle of three numbers, I avoid sorting because it is overkill. Instead, I use a series of comparisons. If a is between b and c, then a is the middle. Similarly, if b is between a and c, b is the middle; otherwise, c is the middle. Specifically, I check if (a > b && a < c) or (a < b && a > c). If neither, I check for b similarly. This approach uses exactly three comparisons in the worst case and avoids the overhead of sorting algorithms, providing an efficient O(1) solution.

Common Mistakes to Avoid

  • Sorting the array unnecessarily
  • Missing edge cases with duplicate values
  • Complex nested conditions that are hard to read

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