Skip to main content

5. Remove Element

easyAsked at Klarna

Remove all occurrences of a value in an array in place and return the new length.

By Sam K., Founder, InterviewChamp.AI · Last verified

Problem

Given an integer array nums and an integer val, remove all occurrences of val in nums in place and return the count of remaining elements. The order of the remaining elements may be changed.

Constraints

  • 0 <= nums.length <= 100
  • 0 <= nums[i] <= 50
  • 0 <= val <= 100

Examples

Example 1

Input
nums = [3,2,2,3], val = 3
Output
2, nums = [2,2,_,_]

Example 2

Input
nums = [0,1,2,2,3,0,4,2], val = 2
Output
5, nums = [0,1,4,0,3,_,_,_]

Approaches

1. Filter copy

Filter to new array then copy back.

Time
O(n)
Space
O(n)
const kept = nums.filter(x => x !== val);
for (let i = 0; i < kept.length; i++) nums[i] = kept[i];
return kept.length;

Tradeoff:

2. Two pointers

Slow pointer is write index; skip over matches as fast scans.

Time
O(n)
Space
O(1)
function removeElement(nums, val) {
  let slow = 0;
  for (let fast = 0; fast < nums.length; fast++) {
    if (nums[fast] !== val) {
      nums[slow] = nums[fast];
      slow++;
    }
  }
  return slow;
}

Tradeoff:

Klarna-specific tips

Klarna favors compaction loops since their risk engine prunes rejected installment offers from candidate arrays in tight inner loops.

Solve it now

Free. No sign-up. Python and JavaScript run instantly in your browser.

Output

Press Run or Cmd+Enter to execute

More Klarna coding interview questions

See all Klarna problems →

Companies that also ask Remove Element