Radix Sort
Detailed guide and Python implementation for the 'Radix Sort' problem.
1. Concept Overview
The 'Radix Sort' problem is a key challenge in the Sorting 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 Radix Sort.
4. Prerequisites
5. Step-by-Step Thinking
1. Understand the problem
Read the problem statement for Radix Sort 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 radix_sort(arr) that sorts a list of non-negative integers arr using the Radix Sort algorithm (using counting sort as the stable sorting subroutine) and returns the sorted list.
- •0 <= len(arr) <= 1000
- •0 <= arr[i] <= 10^6
Examples
arr = [170, 45, 75, 90, 802, 24, 2, 66]
[2, 24, 45, 66, 75, 90, 170, 802]
Sorting is performed digit by digit from least significant digit (LSD) to most significant digit (MSD).
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 counting_sort_for_radix(arr, exp):
n = len(arr)
output = [0] * n
count = [0] * 10
for i in range(n):
index = arr[i] // exp
count[index % 10] += 1
for i in range(1, 10):
count[i] += count[i - 1]
i = n - 1
while i >= 0:
index = arr[i] // exp
output[count[index % 10] - 1] = arr[i]
count[index % 10] -= 1
i -= 1
for i in range(n):
arr[i] = output[i]
def radix_sort_opt(arr):
if not arr: return arr
max1 = max(arr)
exp = 1
while max1 // exp > 0:
counting_sort_for_radix(arr, exp)
exp *= 10
return arrBrute Force Code (Spoiler Guarded)
Brute Force Code (Spoiler Guarded)
def radix_sort_brute(arr):
return radix_sort_opt(arr)Algorithm Pattern Checklist
When dealing with Sorting data patterns.
Core Prerequisites
Revision Key Notes
Common Mistakes & Pitfalls
Related Questions
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