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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.
jordandunmire97-ai
approved these changes
Jun 28, 2026
cclauss
approved these changes
Sep 16, 2026
Fixes the documentation to clarify that 'positions' contains the locations where the pattern was matched.
Corrected grammatical errors in comments and docstrings.
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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:
Closes #13039