Graal Forums - binary

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- - binary_search (https://forums.graalonline.com/forums/showthread.php?t=134256515)

Pelikano

10-16-2009 10:26 PM

binary_search

Should be self explaining...

PHP Code:


		
			
temp.array = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

binary_search(array, 2); // returns true

binary_search(array, 11); // returns false



function binary_search(array, value) {

  temp.volume = array.size();

  temp.middleElement = int(volume/2);

  temp.start = (array[middleElement] < value?middleElement:0);

  temp.end = (start==0?middleElement+1:volume);

  for (i = start; i < end; i++) {

    if (array[i] == value) {

      return true;

    }

  }

  return false;

}

DustyPorViva

10-16-2009 10:29 PM

if (2 in array) true;
else false;

?

Pelikano

10-16-2009 10:32 PM

Quote:

Originally Posted by DustyPorViva (Post 1531038)

if (2 in array) true;
else false;

?

binary_search() is pretty famous.

It's searches a numeric sorted array in an efficient way (usually only used on big arrays).

200'000 Elements -> only searches 100'000.

etc.

coreys

10-17-2009 10:21 AM

Always nice to have around, although I can't think of...well, any use for it, in Graal.
But if the need comes up, then you've got use covered, my boy. :D

Twinny

10-17-2009 10:27 AM

Admittedly I've never have ever thought of a need for this (my arrays are never ordered) but this is one the first algorithms I was taught =)

Binary Search will save you if you have a gigantic sorted array =D

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