Remove Element

Problem Statement

Given an integer array of length $n$ and a value $p$ , remove all elements with the same absolute value as $p$ . This must be done in-place (without creating a new array).


def remove_element(arr, p):
	# Your Code Here

Test Cases

Test Case 1


def test_case_1():
	p = 5
	arr = [3, 4, 5, 2, 1, -5, 5]
	expected = [3, 4, 2, 1]
	remove_element(arr, p)

	assert expected == arr

Test Case 2


def test_case_2():
	p = 1
	arr = [3, 4, 5, 2, 1, -5, 5]
	expected = [3, 4, 5, 2, -5, 5]
	remove_element(arr, p)
	
	assert expected == arr

Click Below to see the Solution

Algorithm

We will use a while loop to go through the indices, but if you remove an item, then don’t increase the index. This is because the array is updated as you go through the loop.

Code


def removeElement(nums, val):
	i = 0
	while i < len(nums):
		if nums[i] == val:
			nums.pop(i)
		else:
			i += 1
	return nums

Runtime Analysis

We iterate through the array exactly once, so the computational complexity is $O(n)$ .