7 lines
327 B
Python
7 lines
327 B
Python
from bisect import bisect_left
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def binary_search(a, x, lo=0, hi=None): # can't use a to specify default for hi
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hi = hi if hi is not None else len(a) # hi defaults to len(a)
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pos = bisect_left(a,x,lo,hi) # find insertion position
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return (pos if pos != hi and a[pos] == x else -1) # don't walk off the end
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