Status: IN
The first-occurrence hash map (record earliest index per key, compute distance on later hits) is a recurring O(n) pattern across the repo, used in largest-substring-between-two-equal-characters, contains-duplicate-ii, check-distances-between-same-letters, and degree-of-an-array.
Source: entries/2026/06/06/largest-substring-between-two-equal-characters-solution.md