25 lines
760 B
CoffeeScript
25 lines
760 B
CoffeeScript
# Uses a binary search algorithm to locate a value in the specified array.
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binary_search = (items, value) ->
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start = 0
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stop = items.length - 1
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pivot = Math.floor (start + stop) / 2
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while items[pivot] isnt value and start < stop
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# Adjust the search area.
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stop = pivot - 1 if value < items[pivot]
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start = pivot + 1 if value > items[pivot]
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# Recalculate the pivot.
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pivot = Math.floor (stop + start) / 2
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# Make sure we've found the correct value.
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if items[pivot] is value then pivot else -1
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# Test the function.
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console.log 2 is binary_search [10, 20, 30, 40, 50], 30
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console.log 4 is binary_search [-97, 35, 67, 88, 1200], 1200
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console.log 0 is binary_search [0, 45, 70], 0
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console.log(-1 is binary_search [0, 45, 70], 10) |