FA-82078 / Poker hand evaluation / Member archive

Ace-to-five wheel treated as a straight in deuce-to-seven · case 03

A-2-3-4-5 is scored as a straight, losing to king-high hands it should beat and never being compared as ace high.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

Input: [hand_a, hand_b] five distinct cards each. Deuce-to-seven lowball: aces are always high, A-2-3-4-5 is not a straight, straights and flushes count against the hand, and the standard high-hand ordering is inverted so the weaker high hand wins. Return 1 if hand_a wins, -1 if hand_b wins, 0 for a tie.

Why this case matters

Lowball variants reuse high-hand evaluators with inverted outcomes, a common source of subtle bugs.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
wheel vs pair	`-1`	`1`	Failed

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