fix: Boyer-Moore bad character shift was dead code in for-loop#14770
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fix: Boyer-Moore bad character shift was dead code in for-loop#14770anyncfunction wants to merge 1 commit into
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The bad_character_heuristic() method used a for-loop with an assignment to the loop variable i, which was immediately overwritten by the next iteration. This caused the algorithm to degrade from O(n/m) to O(n*m) naive search. Changed to a while-loop so the shift actually takes effect. Added max(i+1, shift) guard to prevent backward skips when the mismatched character appears to the right of the mismatch in the pattern. Added edge case doctests.
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Description
The
bad_character_heuristic()method used afor-loop with an assignment to the loop variablei, which was immediately overwritten by the next iteration. This caused the algorithm to degrade from O(n/m) to O(n*m) naive search -- the bad character shift was effectively dead code.Changes
for i in range(...)to awhileloop so the shift actually takes effectmax(i + 1, mismatch_index - match_index)guard to prevent backward skips when the mismatched character appears to the right of the mismatch in the patternVerification
All 12 doctests pass: