FA-84605 / Betting odds conversion / Member archive

Three-to-four band uses the wrong increment · case 05

Prices between 3.00 and 4.00 snap to 0.02 increments.

Member previewVariant 5 · 3 implementations · 9 checks per implementation

Case contract

Snap a requested price onto an exchange tick ladder. Bands in hundredths [lo, hi, step]: [(101, 200, 1), (200, 300, 2), (300, 400, 5), (400, 600, 10), (600, 1000, 20), (1000, 2000, 50), (2000, 3000, 100), (3000, 5000, 200), (5000, 10000, 500), (10000, 100001, 1000)]. Prices outside 1.01..1000 return "invalid". A back request rounds down to a valid tick and a lay request rounds up (ticks counted from the band lower bound). Return the tick as "%d.%02d".

Why this case matters

Exchange order entry must snap arbitrary prices to valid ticks in the customer-safe direction.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
boundary back rounds down	`"3.02"`	`"3.00"`	Failed

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