Both crossovers had an O(n) inner scan making them O(n^2): PMX located the
value to swap with `child.iter().position`, OX tested segment membership
with `segment.contains`. Both operate on strict permutations of 0..n, so a
value-indexed table (PMX: position kept in sync across swaps; OX: a static
membership bitmap) gives O(1) lookups. debug_asserts document the range
assumption, consistent with ERX and CX.
pmx_crossover_vary n=100: 21_507 -> 5_900 (-73%, 3.65x); n=30 -18%.
order_crossover_vary n=100: 18_265 -> 7_389 (-60%, 2.47x); n=30 -29%.
All four permutation crossovers are now O(n). Bit-identical for valid
permutations -- all 606 tests pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
swaitsandClaude Opus 4.7
3b4f765e03