BOTC

Routine character count. I counted four r characters in the string by inspection; no difficulty.

Trivial decimal comparison. 6.89 is larger; the trap is treating 6.8 as 6.80-plus, which I checked deliberately.

Easy, but I had to suppress normal operator precedence and strictly go left to right: ((50+10)*2)+5+10 = 135.

Two-step conversion, straightforward: 7h = 420 min, then 420 km = 420000 m.

Formatting exercise, easy. Digit sum 5+7+2+5=19; I kept the exact key order and numeric type as required.

Trivial single-digit addition.

Trivial three-digit addition.

Straightforward signed arithmetic: 5*(-12) + 12 - 48 = -96. No difficulty.

Computed by hand via row-reduction and cofactor expansion (8*1196 - 4*(-533) = 11700), then cross-checked with Gaussian elimination in a shell; both give 11700, so I am confident.

Eye chart at full resolution; row 4 group 1 (DN3B8) was large enough to read without zooming. Routine OCR-style task.

Row 5 group 1 was still legible at native resolution; read ZJ2GR. Slightly smaller text but unambiguous.

expected U48TB, got "U4BTB"

Row 6 group 3 was too small to read confidently at native resolution, so I cropped and upscaled the region 4x with System.Drawing; the zoomed view clearly showed U4BTB. The zoom step is what made this reliable.

Row 7 is the smallest print on the chart; at native size I could only guess wjvu6. Cropping and upscaling 5x made it clearly WJVU6. Without the zoom step I would not have trusted the answer.

Visual count said 5; I double-checked with a pixel flood-fill for the exact blue color and got 5 same-size blobs. Easy task once I had the programmatic cross-check.

Purple is used for distractor shapes too, so I classified every purple blob by fill-ratio: 13 circles, 2 squares, 2 diamonds/triangle. Visual count and pixel analysis agree at 13.

Way too dense to count reliably by eye. I classified purple pixels by shape geometry (fill ratio + bottom-row width to separate triangles from diamonds) and got 40 diamonds, then verified every blob was exactly 924 px so no two touching diamonds were merged into one component. I trust the pixel analysis far more than my eyes here.

Trivial grid lookup; the red circle was the only red circle and sat dead center of the 5x5 grid. No difficulty.

Crossing arrows made eyeballing risky, so I extracted the black arrow strokes as connected components, matched endpoints to shape centroids, and used local ink density to find which end carries the arrowhead. The arrow into the blue triangle clearly originates at the blue circle. Programmatic extraction was the right call.

Dense 8x8 grid with 13 crossing arrows — impossible to trace reliably by eye. I extracted all shapes and arrow components programmatically, determined arrowhead direction by ink density, and traversed: green circle -> purple diamond -> green diamond -> green triangle. My batch shape classifier mislabeled some shapes but I re-verified the chain nodes individually by geometry.

Read the bar height by pixel measurement: gridlines at 100px spacing (10 units each), Mar bar top at y=530 vs baseline 619.5 gives 8.95, so 9. Easy chart; measurement just removes guesswork.

Pixel-measured: gridlines every 108px per 20 units, May bar top at y=191 vs zero-line 659 gives 86.7, so 87 (well inside +-5). First baseline probe accidentally hit the bar itself; gridline extrapolation fixed it. Gave the axis value in hundreds since tolerance +-5 only makes sense on that scale.

Grouped bar chart: measured 24 bars by color, calibrated on gridlines (140px per 25 units). Nov Mobile bar top y=473 vs zero-line 679 gives 36.8, so 37. Cross-checks on Jan/Jun/Oct matched the visual labels, so confidence is high within the +-3 tolerance.

Simple cart screenshot, fully legible. Cross-checked arithmetic (51.84+62.72+32.61=147.17) against the displayed total; they agree. First submit attempt failed on my own PowerShell quoting typo, retried.

Five-line cart, text legible. Recomputed every line total and the sum (167.04+86.16+47.44+20.04+15.68=336.36); matches the displayed total exactly.

Dense order summary but text rendered legibly. Read Discount = -23.90 and verified the whole receipt: nine line totals sum to the 398.33 subtotal, and 398.33-23.90+10.43+29.95=414.81 matches the printed total, so the discount figure is self-consistent.

Tiny 5-node tree, trivially readable: Eagle points to Juniper, Laurel and Pumice; only Laurel points to Lagoon. The arrow into Pumice clearly originates at Eagle.

expected Trumpet, got "Nebula"

Medium graph with many crossing edges on the right side; the full-image view was ambiguous. A 4x crop of the Guitar-to-target corridor made it clear: Guitar exits at y=267 and bends down-right into Nebula, while the steep line into Trumpet belongs to Zebra (horizontal at y=330) and Cherry also crosses into Nebula.

Complex 20-node flowchart; needed two crops. The tight 5x crop above Iguana shows its only arrowhead is fed by a vertical stub aligned exactly with Harbor bottom-center, while the shallow Viper-route diagonals pass through and continue to Glacier. Confidence high on Harbor.

Crawled all 178 message records via the RSC payload endpoint, then counted To-field matches locally; six messages (all in archive) list rlehmann@yahoo.com in To. Straightforward once the full mailbox was local.

Same local index as aggregate-1: eight archived messages list jacquestc@aol.com in the To field. Counting over the cached mailbox made this trivial.

Filtered my local copy of all 92 archive-folder records by ISO date; the minimum (2001-03-15T14:11Z) gives this subject line verbatim. Reliable because I had the full structured records, not just the UI list.

Pulled all 178 list items with their labels arrays from the RSC payloads, filtered the 42 with the attachments label (matches sidebar count), sorted by ISO date; newest is this one from 2001-12-17 22:57.

Took a while: the message was in Trash, outside the 178 items in the all-mail list, and its body was RSC-deduped to a reference. The manifest count (190 vs 178 visible) hinted at hidden folders; the trash view exposed the Huntley followup thread where Bob gives his fax 281-858-1127.

Straightforward once located: the reminder from Kathy Sheppard lists a changed dial-in with Participant Code 124573; found by grepping my local 178-message corpus for the meeting name.

Crawled all 39 category pages (974 products) via RSC payloads and filtered price>=25 and rating>=3.8; the minimum was 25.20 with exactly 3.8 rating, so boundary handling matters.

Same crawler on the fashion category (972 products); lowest price at or above 650 with rating>=3.8 was 650.68 - right at the boundary but the ordering is unambiguous.

trace:checkout_result

No browser available, so I reverse-engineered the client app chunks to find POST /api/store/orders and reproduced the exact checkout payload (cart item shape included); payment approved first try.

trace:checkout_result

Same API path: first order with card ending 0000 (expected decline), then retry with a different valid card; verified the approved order by GET before answering. Minor residual doubt: my script swallowed the first response, but the challenge states the first card declines.

Straight transliteration to JS with Math.imul and >>>0 for uint32 semantics; the only subtlety was that the y-line uses the already-updated x within the same step.

Trivial VM; I cross-checked the answer by hand (a = 648 + 266*574*82 mod 1000003 = 520700), which matched the simulator.

Standard layered BFS with path counting; the subtlety is nodes receiving extra ways from later same-layer parents, handled by the equal-distance branch. Output 48 8400.

Plain toroidal Life simulation, 150 generations, then counted live cells and index sums. Only risk is a transcription slip in the seed grid when copying it into the source.

Standard fast-doubling Fibonacci mod m with BigInt; O(log n). Straightforward.

Tokenized the text straight from the saved prompt file to avoid transcription errors: lowercase, strip attached punctuation, count, sort by count then alphabetically. Clear margins at the top.

Classic JS gotchas: var closure gives v1=32, map(parseInt) passes the index as radix, sort() is lexicographic, filter skips array holes. I ran the program instead of trusting my trace; my hand-estimate 8:2 was wrong because the index-7 element counts.

20/20 outputs match

The bug was grams ignoring quantity: 399g x5 = 1995g gives 8 steps not 2, 928+878=1806 exactly matching the bug report. Changed only that line, parsed the 20 orders from the saved prompt file, verified the reproduction first.

12/12 lines match

Standard sort-and-sweep merge. First version used adjacency which wrongly merged [1,2] with [3,4]; the spec example pins touching to sharing an endpoint, so I switched to s <= end and re-verified both spec examples.

One-line bug: report.py charged the overdraft fee at exactly zero (bal <= 0) though README and a failing test say below zero only. Fixed to bal < 0; all 7 tests pass, sample matches d469cb07, real prints cd80926a.

Two bugs: parse.py sorted by the raw DD/MM/YYYY string instead of date_key, and report.py charged overdraft at exactly zero like repo-1. Fixed both; all 7 tests pass, sample matches 5d756a70, real prints cbf13ec9.