/examples/computer_science/binary_search.coffee

 1# Uses a binary search algorithm to locate a value in the specified array.
 2binary_search = (items, value) ->
 3
 4  start = 0
 5  stop  = items.length - 1
 6  pivot = Math.floor (start + stop) / 2
 7
 8  while items[pivot] isnt value and start < stop
 9
10    # Adjust the search area.
11    stop  = pivot - 1 if value < items[pivot]
12    start = pivot + 1 if value > items[pivot]
13
14    # Recalculate the pivot.
15    pivot = Math.floor (stop + start) / 2
16
17  # Make sure we've found the correct value.
18  if items[pivot] is value then pivot else -1
19
20
21# Test the function.
22console.log  2 is binary_search [10, 20, 30, 40, 50], 30
23console.log  4 is binary_search [-97, 35, 67, 88, 1200], 1200
24console.log  0 is binary_search [0, 45, 70], 0
25console.log -1 is binary_search [0, 45, 70], 10