Check perfect square using binary search
Quick Overview
This question evaluates a candidate's competency in implementing binary search and handling integer arithmetic and overflow considerations when checking numeric properties. Commonly asked to assess algorithmic complexity analysis and practical coding ability within the Coding & Algorithms domain, it emphasizes practical application and O(log n) performance rather than purely conceptual reasoning.
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Feb 11, 2026, 12:00 AM
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Coding & Algorithms
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Perfect Square Check (Binary Search)
Given a positive integer n, determine whether it is a perfect square (i.e., there exists an integer x such that x*x = n).
Requirements
- Do not use built-in square-root functions.
-
Implement an
O(log n)approach.
Input
-
Integer
n(1 <= n <= 2^31 - 1).
Output
-
Return
trueifnis a perfect square, otherwisefalse.
Examples
-
n = 16->true(4×4) -
n = 14->false
Notes
-
Be careful about integer overflow when computing
mid * mid.