15 LeetCode Patterns, One Real Problem Each

Most coding-interview problems are variations on a small set of patterns. This 33-page guide teaches the recognition skill: 15 patterns with one fully worked example each, 120+ verified practice problems grouped by pattern, clean Java skeletons you can adapt under time pressure, a 60-second triage for deciding which pattern a problem wants, and a drill set per pattern. Written by an engineer who interviews at Amazon and failed these rounds before passing them.