Program to calculate length of string using recursion
Detailed guide and Python implementation for the 'Program to calculate length of string using recursion' problem.
1. Concept Overview
The 'Program to calculate length of string using recursion' problem is a key challenge in the Recursion section.
This implementation focuses on medium-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 Program to calculate length of string using recursion.
4. Prerequisites
5. Step-by-Step Thinking
1. Understand the problem
Read the problem statement for Program to calculate length of string using recursion 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 string_length(s) that calculates and returns the length of the string s using recursion. You must NOT use the built-in len() function. The base case is an empty string which has length 0. For each recursive call, count one character and recurse on the remaining string.
- •0 <= len(s) <= 1000
- •s contains only printable ASCII characters
Examples
s = 'hello'
5
The string 'hello' has 5 characters: h, e, l, l, o.
s = 'python'
6
The string 'python' has 6 characters.
s = ''
0
An empty string has length 0.
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 string_length(s, count=0):
if not s:
return count
return string_length(s[1:], count + 1)Brute Force Code (Spoiler Guarded)
Brute Force Code (Spoiler Guarded)
def string_length(s):
if s == "":
return 0
return 1 + string_length(s[1:])Algorithm Pattern Checklist
When dealing with Recursion 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 Strings
Master string manipulation in Python. Learn string methods, slicing, concatenation, and formatting techniques with clear, executable code examples.
How to Reverse a String in Python
Learn how to reverse a string in Python using slicing, the reversed() function, and loop concatenation with visual code examples.
Python String Methods
A complete reference guide for Python string manipulation. Master formatting, searching, splitting, replacing, and checking string properties.
Python Decorators vs Decorator Design Pattern: The Key Differences
Compare Python decorators and the classic decorator design pattern. Understand the differences between definition-time function wrapping and runtime dynamic object composition with runnable code.