Missing Number - Blind 75 - Leetcode 268 - Python

Picked one by one from a mixed channel. Transcript check: both title readers certain; channel sample of 8 certain picks all confirmed by transcript. Channel rule: Include only the coding-problem walkthroughs whose titles name a specific 'Leetcode <number>' problem (e.g., 'Two Sum - Leetcode 1 - Python'); exclude AI news/opinion, personal stories, mock interviews, listicle-style concept roundups and anything with a question or hook title.