# Create Sorted List

sorted_list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20] print(sorted_list)

[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20]

## Creat a binary search algorithm

def binary_search(sorted_list, target): '''This function inputs a sorted list and a target value to find and returns ....''' # Create variables for the index of the first and last elements start = 0 end = len(sorted_list) - 1 while end >= start: # Create a variable for the index of the middle term middle = start + (end - start) // 2 # // is integer division in Python 3.X # If the target value is less than the middle value of the search area if target < sorted_list[middle]: # Cut the list in half by making the new end value the old middle value minus 1 # The minus one is because we already ruled the middle value out, so we can ignore it end = middle - 1 # Else, if the target value is greater than the middle value of the search area elif target > sorted_list[middle]: # Cut the list in half by making the new start value the old middle value plus 1 # The plus one is because we already ruled the middle value out, so we can ignore it start = middle + 1 # If it's not too high or too low, it must be just right, return the location else: return ("Found it at index: {}".format(middle)) # If we've fallen out of the while loop the target value is not in the list return print("Not in list!")

binary_search(sorted_list, 2)

'Found it at index: 1'

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