Number of 1 Bits
Detailed guide and Python implementation for the 'Number of 1 Bits' problem.
1. Concept Overview
The 'Number of 1 Bits' problem is a key challenge in the Bit Manipulation section.
This implementation focuses on easy-level logic in Python.
We prioritize technical accuracy and code readability in our provided solutions.
2. Real-World Applications
3. Visual Intuition
Visualizing the logic flow for Number of 1 Bits.
4. Prerequisites
5. Step-by-Step Thinking
1. Understand the problem
Read the problem statement for Number of 1 Bits carefully.
2. Formulate brute force
Draft a simple iterative solution.
3. Identify inefficiency
Look for redundant calculations.
4. Optimize search path
Use hashing or sorting to speed up the process.
5. Final Implementation
Clean up the code for production standards.
Problem Statement
Write a function that takes the binary representation of a positive integer and returns the number of set bits it has (also known as the Hamming weight).
Write a function hammingWeight(n: int) -> int.
- •n must be a positive integer up to 2^32 - 1
Examples
n = 11
3
The binary representation of 11 is 1011, which has 3 set bits.
n = 128
1
The binary representation of 128 is 10000000, which has 1 set bit.
Need a Hint?
Edge Cases to Watch
- Empty input structures
- Single element inputs
- Large numerical bounds
Ready to Solve?
Open the problem in PyRun's browser-based Python editor. Your code runs fully offline — no server required.
Interview Insights & Variations
Complexity Analysis Breakdown
Why Time: Directly evaluates all possibilities.
Why Space: Uses standard local memory.
Why Time: Optimized paths reduce total operations.
Why Space: May trade memory for speed.
Optimized Solution Python Code
Optimized Solution Python Code
def hamming_weight_opt(n):
res = 0
while n:
n &= (n - 1); res += 1
return resBrute Force Code (Spoiler Guarded)
Brute Force Code (Spoiler Guarded)
def hamming_weight_brute(n):
return bin(n).count("1")Algorithm Pattern Checklist
When dealing with Bit Manipulation data patterns.
Core Prerequisites
Revision Key Notes
Common Mistakes & Pitfalls
Related Questions
Recommended Python Resources
Expand your knowledge with related interactive tutorials, cheat sheets, and code comparisons.
Python Loops
Learn how to use Python loops to iterate over data. Master for loops, while loops, break, continue, and loop best practices with interactive examples.
How to Find the Length of a List in Python
Learn how to find the length of a list in Python using the len() function. Understand the O(1) time complexity and checking counts.
Python String Methods
A complete reference guide for Python string manipulation. Master formatting, searching, splitting, replacing, and checking string properties.
Python vs JavaScript: Which Programming Language is Best?
A comprehensive comparison between Python and JavaScript. Explore syntax differences, performance, use cases (backend vs frontend), and coding examples.