25 lines
648 B
Ruby
25 lines
648 B
Ruby
class Array
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def binary_search(val, low=0, high=(length - 1))
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return nil if high < low
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mid = (low + high) / 2
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case
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when self[mid] > val then binary_search(val, low, mid-1)
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when self[mid] < val then binary_search(val, mid+1, high)
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else mid
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end
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end
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end
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def do_a_binary_search(val, ary, method)
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i = ary.send(method, val)
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if i
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puts "found #{val} at index #{i}: #{ary[i]}"
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else
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puts "#{val} not found in array"
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end
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end
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ary = [0,1,4,5,6,7,8,9,12,26,45,67,78,90,98,123,211,234,456,769,865,2345,3215,14345,24324]
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do_a_binary_search(45, ary, :binary_search)
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do_a_binary_search(42, ary, :binary_search)
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