🧠 Solving LeetCode Until I Become Top 1% — Day `54`

🔹 Problem: Power of Two

Difficulty: #Easy
Tags: #Math #BitManipulation

📝 Problem Summary

Given an integer n, determine if it is a power of two. A number is a power of two if it can be written as 2^k for some integer k ≥ 0.
Ret…


This content originally appeared on DEV Community and was authored by Md. Rishat Talukder

🔹 Problem: Power of Two

Difficulty: #Easy
Tags: #Math #BitManipulation

📝 Problem Summary

Given an integer n, determine if it is a power of two. A number is a power of two if it can be written as 2^k for some integer k ≥ 0.
Return True if n is a power of two, otherwise return False.

🧠 My Thought Process

  • Brute Force Idea:

    • Keep dividing n by 2 while it’s even.
    • If we ever hit an odd number before n becomes 1, it’s not a power of two.
    • If we reach 1 exactly, it is a power of two.
    • This works because a power of two in binary has exactly one 1 bit.

  • Optimized Strategy:

    • Use bitwise trick: n > 0 and (n & (n - 1)) == 0 This works because powers of two have exactly one bit set, so subtracting 1 flips that bit and sets all bits after it to 1. AND-ing them results in 0.
    • But here, I implemented the division approach, which is still O(log n) and easy to understand.

  • Algorithm Used:

    Simple iterative division check.

⚙️ Code Implementation (Python) 

class Solution:
    def isPowerOfTwo(self, n: int) -> bool:
        while n != 1:
            if n % 2 == 1 or n == 0:
                return False
            n //= 2
        return True

⏱️ Time & Space Complexity

  • Time: O(log n) — Each step halves n.
  • Space: O(1) — No extra memory used.

🧩 Key Takeaways

  • ✅ Powers of two in binary have only one bit set.
  • 💡 Division method is beginner-friendly, bitwise method is constant-time.
  • 💭 If a problem involves checking for power of two, consider both math and bit tricks.

🔁 Reflection (Self-Check)

  • [x] Could I solve this without help?
  • [x] Did I write code from scratch?
  • [x] Did I understand why it works?
  • [x] Will I be able to recall this in a week?

📚 Related Problems

🚀 Progress Tracker

Metric Value
Day 54
Total Problems Solved 410
Confidence Today 😃
Leetcode Rating 1572


This content originally appeared on DEV Community and was authored by Md. Rishat Talukder


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