/examples/computer_science/binary_search.coffee

http://github.com/jashkenas/coffee-script · CoffeeScript · 25 lines · 13 code · 7 blank · 5 comment · 5 complexity · c2ff8a0bb6d2152427809982f7b7330e MD5 · raw file

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