Program to reverse a list by list slicing in Python

List slicing in Python provides a simple and efficient way to reverse a list using the slice notation [::-1]. This approach creates a new list with elements in reverse order without modifying the original list.

Understanding List Slicing Syntax

List slicing takes three parameters separated by colons: [start:end:step]

• start − Starting index (default: 0)
• end − Ending index (default: length of list)
• step − Step size (default: 1)

For reversing, we use [::-1] where:

• Empty start and end means include entire list
• -1 step means move backwards through the list

Example

Here's how to reverse a list using slicing ?

def solve(nums):
    return nums[::-1]

nums = [5, 7, 6, 4, 6, 9, 3, 6, 2]
reversed_nums = solve(nums)

print("Original list:", nums)
print("Reversed list:", reversed_nums)

Original list: [5, 7, 6, 4, 6, 9, 3, 6, 2]
Reversed list: [2, 6, 3, 9, 6, 4, 6, 7, 5]

Direct Slicing Without Function

You can also reverse a list directly without creating a function ?

nums = [5, 7, 6, 4, 6, 9, 3, 6, 2]
reversed_nums = nums[::-1]

print("Original:", nums)
print("Reversed:", reversed_nums)
print("Original unchanged:", nums)

Original: [5, 7, 6, 4, 6, 9, 3, 6, 2]
Reversed: [2, 6, 3, 9, 6, 4, 6, 7, 5]
Original unchanged: [5, 7, 6, 4, 6, 9, 3, 6, 2]

Key Points

• List slicing with [::-1] creates a new list
• The original list remains unchanged
• This method works with any sequence type (strings, tuples)
• Time complexity is O(n) where n is the length of the list

Conclusion

List slicing with [::-1] is the most Pythonic way to reverse a list. It's concise, readable, and creates a new reversed list without modifying the original.