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Longest Common Subsequence is a medium coding interview question covering dynamic programming, strings — the kind asked at FAANG (Facebook/Meta, Apple, Amazon, Netflix, Google) and AI-first companies like Anthropic, OpenAI, and Nvidia.
Given two strings text1 and text2, return the length of their longest common subsequence (LCS).
A subsequence is formed by deleting characters without changing relative order.
Example: text1="abcde", text2="ace" -> 3 (LCS is "ace") Example: text1="abc", text2="def" -> 0
Classic DP problem used in diff tools (git diff), bioinformatics (DNA alignment), and plagiarism detection.
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