When it is required to reverse a rotated array, a method is defined, that iterates through the list and reverse the list. Another method is defined, that rotates the list, and another method is defined that displays the list. A simple loop and indexing is used to achieve this.
Below is a demonstration for the same −
Example
def reverse_list(my_list, begin, end):
while (begin < end):
temp = my_list[begin]
my_list[begin] = my_list[end]
my_list[end] = temp
begin += 1
end = end-1
def left_rotate(my_list, to_rotate):
n = len(my_list)
reverse_list(my_list, 0, to_rotate-1)
reverse_list(my_list, to_rotate, n-1)
reverse_list(my_list, 0, n-1)
def print_it(my_list):
for i in range(0, len(my_list)):
print(my_list[i])
my_list = [34, 42, 56, 78, 9, 0, 23]
print("The list is :")
print(my_list)
print("The left_rotate method is being called")
left_rotate(my_list, 3)
print("The list after rotation is : ")
print_it(my_list)Output
The list is : [34, 42, 56, 78, 9, 0, 23] The left_rotate method is being called The list after rotation is : 78 9 0 23 34 42 56
Explanation
- A method named ‘reverse_list’ is defined, that reverses the given list.
- Another method named ‘rotate_list’ is defined, that rotates the list based on a specific pivot value.
- Another method named ‘print_it’ is defined, that prints the list on the console.
- A list is defined, and is displayed on the console.
- The ‘left_rotate’ method is called on this list, and elements are displayed on the console after rotation and reversal.