DSA · Two pointers (string) · #25
Valid Palindrome
Module 28 · difficulty 1/5·⏱ 30:00starts on first keystroke
A phrase is a palindrome if, after lowercasing and removing all non-alphanumeric characters, it reads the same forwards and backwards. Given a string `s`, return `true` if it is a palindrome, `false` otherwise.
Examples
s = "A man, a plan, a canal: Panama"→trues = "race a car"→falses = " "→true— empty after cleaning
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Constraints
- · 1 <= s.length <= 2·10^5
- · s consists of printable ASCII characters.
Session phases
A · Clarify
B · Approach
C · Complexity
D · Edges
E · Code
F · Tradeoff
G · Score
Phase A — Clarify
Ask questions about input bounds, types, and edge constraints.
Ask the coach clarifying questions about the problem.
When you've covered this phase, advance to the next.