Binary Search

Sun, 04 Apr 2021 00:00:00 +0000

Binary search only works when your list is in sorted order.

Code

def binary_search(list, item):
 # keep track of low and high
 low = 0
 high = len(list) - 1

 while low <= high: # when we haven't narrowed down to one element
 mid = (low + high) // 2 # index of the middle element
 guess = list[mid] # value of the middle element

 if guess == item:
 return mid
 elif guess > item:
 # Guess is too high,
 # we narrow our search on the "left" part
 high = mid - 1
 else:
 # Guess is too low,
 # we narrow our search on the "right" part
 low = mid + 1

 # If we have anrrowed down to one element but still can not find the item
 # => Item is not in the list 
 return -1

Binary Search | Haobin Tan

Binary Search

Code

Complexity

Binary Vs Linear Search

Average Case

Binary Search Worst Case

Binary Search Best Case