gh-119105: difflib.py Differ.compare is too slow [for degenerate cases] #119376
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estyxx
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…e cases] (python#119376) Track all pairs achieving the best ratio in Differ(). This repairs the "very deep recursion and cubic time" bad cases in a way that preserves previous output.
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A different approach, tracking all ascending index pairs achieving the best ratio. None of them needs recursion then. And, more importantly, it restores difflib's general "top to bottom" ordering of matches.