Python Program to Split the Array and Add First Part to the End (original) (raw)

Last Updated : 11 Nov, 2025

Given an array and an integer k, the task is to split the array from the kth position and move the first part to the end. For Example:

**Input: arr = [12, 10, 5, 6, 52, 36], k = 2
**Output: [5, 6, 52, 36, 12, 10]
**Explanation: Split the array at index k and move the first part [12, 10] (for k = 2) to the end.

Below are the different methods to perform this task:

Using deque.rotate() from collections

deque from the collections module allows efficient rotation of elements. Its rotate() method handles both left and right rotations internally without explicit shifting.

Python `

from collections import deque

arr = [12, 10, 5, 6, 52, 36] k = 2

d = deque(arr) d.rotate(-k) print(list(d))

`

Output

[5, 6, 52, 36, 12, 10]

**Explanation:

• **deque(arr): converts the list into a double-ended queue
• **rotate(-k): shifts the elements left by k positions
• **list(d): converts the deque back into a list

Using List Slicing

List slicing rotates a list by splitting it at position k taking elements from index k to the end first, then adding the first k elements to the end.

Python `

arr = [12, 10, 5, 6, 52, 36] k = 2

arr = arr[k:] + arr[:k] print(arr)

`

Output

[5, 6, 52, 36, 12, 10]

**Explanation:

• **arr[:k]: first k elements.
• **arr[k:]: remaining elements.
• Concatenating them gives the rotated array.

Using List Comprehension and Modulo

This method uses modular arithmetic to calculate rotated positions directly. It constructs a new list where each element is taken from (i + k) % len(arr).

Python `

arr = [12, 10, 5, 6, 52, 36] k = 2

n = len(arr) res = [arr[(i + k) % n] for i in range(n)] print(res)

`

Output

[5, 6, 52, 36, 12, 10]

**Explanation:

• ****(i + k) % len(arr):** wraps indices around the array, ensuring the rotation is circular.
• Creates a rotated version without modifying the original array.

Using extend()

Slicing combined with extend() achieves rotation while demonstrating list merging explicitly.

Python `

arr = [12, 10, 5, 6, 52, 36] k = 2

x = arr[:k] y = arr[k:] y.extend(x) print(y)

`