How do you solve Power of Three on LeetCode?

Power of Three (LeetCode #326) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(1) time complexity and O(1) space complexity. Key insight: Understanding logarithms can simplify problems involving powers.

What is the brute force solution for Power of Three?

The brute force approach for Power of Three is Brute Force, with O(log n) time complexity and O(1) space complexity. The brute force approach checks if we can keep dividing the number n by 3 until we reach 1. If we can do this without leaving a remainder, then n is a power of three. The optimal Optimal Solution approach improves this to O(1).

What algorithm or data structure is used to solve Power of Three?

Power of Three uses the following concepts: Math, Recursion. The recommended patterns to study are: Mathematical properties, Logarithmic calculations.

What are the interview tips for Power of Three?

Always consider edge cases first. Explain your thought process clearly, especially when using mathematical concepts. Practice both iterative and mathematical approaches to gain confidence.

What are common mistakes when solving Power of Three?

Confusing powers with multiples (e.g., thinking 6 is a power of 3). Not handling edge cases like n = 0 or negative numbers.

#326

Power of Three

Easy

MathRecursionMathematical propertiesLogarithmic calculations

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

	Brute Force	Optimal Solution★
Time	O(log n)	O(1)
Space	O(1)	O(1)

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Intuition

Time O(1)Space O(1)

Instead of dividing repeatedly, we can use logarithms to check if n is a power of three. If log base 3 of n is an integer, then n is a power of three.

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Algorithm

3 steps

1Step 1: If n is less than or equal to 0, return false.
2Step 2: Calculate log base 3 of n using the change of base formula: log(n) / log(3).
3Step 3: Check if the result is an integer by comparing it to its rounded value.

solution.py8 lines

1# Full working Python code
2import math
3
4def isPowerOfThree(n):
5    if n <= 0:
6        return False
7    log_result = math.log(n, 3)
8    return log_result.is_integer()

ℹ

Complexity note: The time complexity is O(1) because we are performing a constant number of operations regardless of the size of n. The space complexity is also O(1) since we are using a constant amount of space.

1Understanding logarithms can simplify problems involving powers.
2Checking for powers of numbers can often be done using mathematical properties.

Solutions and explanations are original Tejav content. Problem titles © LeetCode — use the LeetCode button above for the full problem statement.