Minimum Number of Flips to Make the Binary String Alternating LeetCode solution in Python

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# Runtime: 631 ms (Top 87.94%) | Memory: 14.8 MB (Top 94.52%)
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class Solution:
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    def minFlips(self, s: str) -> int:
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        prev = 0
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        start_1, start_0, start_1_odd, start_0_odd = 0, 0, sys.maxsize, sys.maxsize
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        odd = len(s) % 2
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        for val in s:
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            val = int(val)
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            if val == prev:
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                if odd:
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                    start_0_odd = min(start_0_odd, start_1)
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                    start_1_odd += 1
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                start_1 += 1
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            else:
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                if odd:
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                    start_1_odd = min(start_1_odd, start_0)
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                    start_0_odd += 1
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                start_0 += 1
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            prev = 1 - prev
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        return min([start_1, start_0, start_1_odd, start_0_odd])