Week 4 Cold Revisit

This Friday, before any new work, re-solve two prior problems cold: no notes, no prior code open, no AI, the standard 25-minute struggle floor on each. The first solve taught the pattern; this blind re-solve is what makes it stick.

The two problems

  1. Group Anagrams (Week 1, Arrays and Hashing). https://leetcode.com/problems/group-anagrams/
  2. Trapping Rain Water (Week 2, Two Pointers). https://leetcode.com/problems/trapping-rain-water/

How to run the revisit

  • Do not look up which pattern either problem belongs to. Recognizing it cold, from the problem statement alone, is the entire point of the exercise; the tutor will not tell you.
  • Start each from a blank file. Name the pattern aloud, write the plain-English approach as a comment, then code.
  • Apply the 25-minute floor to each independently. If you stall past the floor, use the hint ladder, one rung per ask.
  • Submit each to LeetCode’s judge. The judge is the oracle, not the tutor.
  • Debrief each with the five questions in your commit message, and log the outcome in .tutor/revisit-log.md.

Neither problem is a stack problem, and that is deliberate. The cold revisit trains recognition across the whole course, so the muscle you build is “read a cold statement and feel the pattern”, not “apply this week’s pattern again”. Trapping Rain Water is a useful one to meet again right now, because it can be solved with a stack (you just spent a week on stacks), yet its cleanest solution is the two-pointer method from Week 2; let yourself recognize it fresh rather than forcing this week’s tool onto it. If either problem comes back slower than you expect, that is the signal for where to spend your next stretch session.