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📜 WAYPOINT LESSON

The clause that decides

⭐⭐⭐ advanced⏳ 10 min read📍 Lesson 209 of 256

Tie-breaks, strictness, sentinels, format rules — circle every operator-deciding word; the circles are the rubric.

The hardest single-method FRQs fail students on one clause, not on the algorithm. The clause types, in order of appearance on real exams:

  • Tie-break clauses: "on a tie, return the one appearing FIRST/SMALLEST." Your loop's comparison must implement the tie-break exactly — > keeps the first-seen; >= keeps the last.
  • Strictness clauses: "more than," "at least," "strictly between." Each maps to an operator; underline them.
  • Sentinel clauses: "return -1/0.0/999 if none." A sentinel forces a two-variable scan (the candidate and a found-flag) or an early return — one accumulator cannot serve both jobs.
  • Format clauses: "adjacent duplicates are replaced by a star" — output-shaping specs where the boundary iteration (start at index 1, compare backward) is the entire difficulty.

Read the spec once for the story, then a second time circling every operator-deciding word. Those circles are the rubric.