The same occurrences, and the two things one traversal has to remember

The same occurrences, and the two things one traversal has to remember

8 patterns of 6 characters on a collection of 8 near-copies, 3,072 characters, 205 phrases. Each row is one query: the occurrences found, the visited set the published queue holds, and the largest frontier the sweep holds. The two traversals examine exactly the same 17,715 phrases and report exactly the same occurrences — that is the check, and a difference would be a wrong answer rather than a slower one. What differs is the bookkeeping: the queue keeps every occurrence found so far in a set, and the sweep keeps one ordered list and a cursor.

Drawn at 700 × 362, wide on the page. Everything above is what phrase-sweep returns with no arguments; the caption is the generator's own, computed from the numbers in the drawing rather than written beside it.

6 essays call phrase-sweep. The drawing above is what it returns with no arguments at all; every call below passes it something, because a placement that passes nothing draws whichever member of the family the generator happens to default to rather than the one its essay argues about — which is what optcheck and figfill exist to catch.