Python program to interchange first and last elements in a list

Given a list, write a Python program to swap first and last element of the list.

Examples:

Input : [12, 35, 9, 56, 24]
Output : [24, 35, 9, 56, 12]

Input : [1, 2, 3]
Output : [3, 2, 1]

Approach #1: Find the length of the list and simply swap the first element with (n-1)th element.

# Python3 program to swap first # and last element of a list    # Swap function def swapList(newList):     size = len(newList)            # Swapping      temp = newList[0]     newList[0] = newList[size - 1]     newList[size - 1] = temp            return newList        # Driver code newList = [12, 35, 9, 56, 24]    print(swapList(newList))

Output:

[24, 35, 9, 56, 12]

 
Approach #2: The last element of the list can be referred as list[-1]. Therefore, we can simply swap list[0] with list[-1].

# Python3 program to swap first # and last element of a list    # Swap function def swapList(newList):            newList[0], newList[-1] = newList[-1], newList[0]        return newList        # Driver code newList = [12, 35, 9, 56, 24] print(swapList(newList))

Output:

[24, 35, 9, 56, 12]

 
Approach #3: Swap the first and last element is using tuple variable. Store the first and last element as a pair in a tuple variable, say get, and unpack those elements with first and last element in that list. Now, the First and last values in that list are swapped.

# Python3 program to swap first # and last element of a list    # Swap function def swapList(list):            # Storing the first and last element      # as a pair in a tuple variable get     get = list[-1], list[0]            # unpacking those elements     list[0], list[-1] = get            return list        # Driver code newList = [12, 35, 9, 56, 24] print(swapList(newList))

Output:

[24, 35, 9, 56, 12]

 
Approach #4: Using * operand.
This operand proposes a change to iterable unpacking syntax, allowing to specify a “catch-all” name which will be assigned a list of all items not assigned to a “regular” name.

# Python3 program to illustrate  # the usage of * operarnd list = [1, 2, 3, 4]    a, *b, c = list    print(a) print(b) print(c)

Output:

1
[2, 3]
4

Now let’s see the implementation of above approach:

# Python3 program to swap first # and last element of a list    # Swap function def swapList(list):            start, *middle, end = list     list = [end, *middle, start]            return list        # Driver code newList = [12, 35, 9, 56, 24]    print(swapList(newList))

Output:

[24, 35, 9, 56, 12]

 

Approach #5: Swap the first and last elements is to use inbuilt function list.pop(). Pop the first element and store it in a variable. Similarily pop the last element and store it in another variable. Now insert the two popped element at each other’s original position.

# Python3 program to swap first # and last element of a list    # Swap function def swapList(list):            first = list.pop(0)        last = list.pop(-1)            list.insert(0, last)       list.append(first)               return list        # Driver code newList = [12, 35, 9, 56, 24]    print(swapList(newList))

Output:

[24, 35, 9, 56, 12]