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5. Remove Element

easyAsked at Squarespace

Remove all occurrences of a value in-place; Squarespace screens use it to test in-place mutation discipline.

By Alex Chen, Founder, InterviewChamp.AI · Last verified

Problem

Given an integer array nums and a value val, remove every occurrence of val in-place and return the new length k.

Constraints

  • 0 <= nums.length <= 100
  • 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

Approaches

1. Filter + rewrite

Filter to a new array then copy back.

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

Tradeoff:

2. Two pointers

Slow pointer keeps non-val items; fast pointer scans.

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

Tradeoff:

Squarespace-specific tips

Squarespace wants you to call out that in-place removal mirrors how their CMS prunes deleted blocks from an array of section IDs without reallocating.

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Output

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