#two pointers

AI Dev Tools

LeetCode 647: Palindromic Substrings, the O(n²) Workhorse That Won't Die

Twenty years in tech, and palindromes still trip up FAANG hopefuls. LeetCode 647's expand-around-centers nails it without wasting space—here's why it endures.

AI Dev Tools

Sliding Through Chaos: Mastering LeetCode 424's Character Replacement Puzzle

Picture this: a string of letters twisting like a DNA strand, and you've got k swaps to forge the longest uniform run. LeetCode 424 drops you right in—here's the vivid trace that makes it click.