Lecture 85:-  Check if a List is Sorted In Python

You can check if a list is sorted in Python by comparing each element with its adjacent element. If all elements are in ascending order (or descending order for a reverse sort), then the list is considered sorted.

Here's a simple function to check if a list is sorted in ascending order:

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def is_sorted(lst):    return all(lst[i] <= lst[i + 1] for i in range(len(lst) - 1)) # Example usage: sorted_list = [1, 3, 5, 7, 9] unsorted_list = [3, 2, 1, 4, 5] print(is_sorted(sorted_list))    # Output: True print(is_sorted(unsorted_list))  # Output: False

In this example, the is_sorted() function takes a list as input and uses a list comprehension along with the all() function to check if each element (lst[i]) is less than or equal to the next element (lst[i + 1]). If all elements meet this condition, the function returns True, indicating that the list is sorted. Otherwise, it returns False.

To check if the list is sorted in descending order, you can modify the condition in the is_sorted() function to use the >= operator instead of <=.

Keep in mind that the is_sorted() function assumes that the list elements are comparable, meaning they support the comparison operators (<, >, <=, >=). If the list contains complex objects or custom classes, you may need to define a custom sorting criteria or use the sorted() function with a custom comparison function to check for sorting.