4.4. Reverse Left

You are given a list of integers and a single integer from that list. The first occurrence of that integer divides our list to 2 sub-lists, left sub-list and right sub-list.

Write a function called reverse_left that takes a list of integers and an integer in that list, and reverses the left sub-list of a given list. The function should return a new list.

Note that the same integer can occur any number of times in the right sub-list.

Hint: There are list methods for finding the first occurrence of an element and reversing a list.

Sample I/O:

>>> reverse_left([8,1,4,5,6,6,3,2], 6)
[5,4,1,8,6,6,3,2]

>>> reverse_left([64, 51, 77, 34, 77, 39, 57, 67, 58, 63, 51], 39)
[77, 34, 77, 51, 64, 39, 57, 67, 58, 63, 51]

Show the Answer

def reverse_left(i_list, occurrence):
    occurrence_index = i_list.index(occurrence)           #finding the index of the first occurrence

    left_sub_list = i_list[:occurrence_index]             #constructing the left sub-list
    left_sub_list.reverse()                               #reversing the left sub-list
    right_sub_list = i_list[occurrence_index:]            #constructing the right sub-list

    return left_sub_list + right_sub_list