Compute longest common subsequence length
Company: Roku
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Onsite
## Problem
You are given two strings `s` and `t`. A **subsequence** of a string is obtained by deleting zero or more characters without changing the order of the remaining characters.
Return the **length** of the **longest common subsequence (LCS)** between `s` and `t`.
## Input
- Two strings `s`, `t`
## Output
- An integer: the length of the LCS of `s` and `t`
## Constraints (typical interview bounds)
- `0 <= len(s), len(t) <= 1000`
- Strings contain lowercase/uppercase letters (assume ASCII letters)
## Examples
- `s = "abcde"`, `t = "ace"` → output `3` (LCS could be `"ace"`)
- `s = "abc"`, `t = "def"` → output `0`
Quick Answer: This question evaluates understanding of dynamic programming and sequence processing, measuring competence in reasoning about optimal substructure, overlapping subproblems, and algorithmic complexity.