Week 15 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. Edit Distance (Week 14, 2-D Dynamic Programming). https://leetcode.com/problems/edit-distance/
  2. Cheapest Flights Within K Stops (Week 12, Advanced Graphs). https://leetcode.com/problems/cheapest-flights-within-k-stops/

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 of these is this week’s pattern, and that pairing is deliberate. This week’s material (greedy, bit tricks, matrix bookkeeping) is light and self-contained, and the danger of a light week is that the hardest machinery you built recently quietly decays while you are not using it. So this Friday reaches back to the two heaviest things you have done. Edit Distance is the canonical two-string DP from Week 14, where the whole game is defining dp[i][j] and the match/mismatch transition; re-solving it keeps the state-definition skill sharp. Cheapest Flights Within K Stops is the Advanced Graphs canonical from Week 12, the course’s heaviest, most algorithm-dense week, where the move is state expansion: the state is (node, stops_used), not the node alone, and you solve it Bellman-Ford-by-rounds. This is the one fixed cold re-test the Advanced Graphs family gets before the Week 16 marathon, so recognizing it cold and rebuilding the expanded state from a blank file is the whole point. If either comes back slower than you expect, that is the signal for where to spend your next stretch session, and a flag that that week deserves another pass before the Week 16 marathon.