Leetcode #2129: Capitalize the Title
In this guide, we solve Leetcode #2129 Capitalize the Title in Python and focus on the core idea that makes the solution efficient.
You will see the intuition, the step-by-step method, and a clean Python implementation you can use in interviews.
Problem Statement
You are given a string title consisting of one or more words separated by a single space, where each word consists of English letters. Capitalize the string by changing the capitalization of each word such that: If the length of the word is 1 or 2 letters, change all letters to lowercase.
Quick Facts
- Difficulty: Easy
- Premium: No
- Tags: String
Intuition
We need to scan characters while tracking positions or counts.
A simple state machine keeps the logic precise.
Approach
Iterate through the string once and update the state for each character.
Use a map or array if you need fast lookups.
Steps:
- Iterate through characters.
- Maintain necessary state.
- Build or validate the output.
Example
Input: title = "capiTalIze tHe titLe"
Output: "Capitalize The Title"
Explanation:
Since all the words have a length of at least 3, the first letter of each word is uppercase, and the remaining letters are lowercase.
Python Solution
class Solution:
def capitalizeTitle(self, title: str) -> str:
words = [w.lower() if len(w) < 3 else w.capitalize() for w in title.split()]
return " ".join(words)
Complexity
The time complexity is , and the space complexity is , where is the length of the string title. The space complexity is , where is the length of the string title.
Edge Cases and Pitfalls
Watch for boundary values, empty inputs, and duplicate values where applicable. If the problem involves ordering or constraints, confirm the invariant is preserved at every step.
Summary
This Python solution focuses on the essential structure of the problem and keeps the implementation interview-friendly while meeting the constraints.