RemoveElement.ts

// Source : https://leetcode.com/problems/remove-element/
// Author : squxq
// Date   : 2023-09-08

/** ***************************************************************************************************
 *
 * Given an integer array nums and an integer val, remove all occurrences of val in nums in-place. The
 * order of the elements may be changed. Then return the number of elements in nums which are not
 * equal to val.
 *
 * Consider the number of elements in nums which are not equal to val be k, to get accepted, you need
 * to do the following things:
 *
 * 	Change the array nums such that the first k elements of nums contain the elements which are
 * not equal to val. The remaining elements of nums are not important as well as the size of nums.
 * 	Return k.
 *
 * Custom Judge:
 *
 * The judge will test your solution with the following code:
 *
 * int[] nums = [...]; // Input array
 * int val = ...; // Value to remove
 * int[] expectedNums = [...]; // The expected answer with correct length.
 *                             // It is sorted with no values equaling val.
 *
 * int k = removeElement(nums, val); // Calls your implementation
 *
 * assert k == expectedNums.length;
 * sort(nums, 0, k); // Sort the first k elements of nums
 * for (int i = 0; i < actualLength; i++) {
 *     assert nums[i] == expectedNums[i];
 * }
 *
 * If all assertions pass, then your solution will be accepted.
 *
 * Example 1:
 *
 * Input: nums = [3,2,2,3], val = 3
 * Output: 2, nums = [2,2,_,_]
 * Explanation: Your function should return k = 2, with the first two elements of nums being 2.
 * It does not matter what you leave beyond the returned k (hence they are underscores).
 *
 * Example 2:
 *
 * Input: nums = [0,1,2,2,3,0,4,2], val = 2
 * Output: 5, nums = [0,1,4,0,3,_,_,_]
 * Explanation: Your function should return k = 5, with the first five elements of nums containing 0,
 * 0, 1, 3, and 4.
 * Note that the five elements can be returned in any order.
 * It does not matter what you leave beyond the returned k (hence they are underscores).
 *
 * Constraints:
 *
 * 	0 <= nums.length <= 100
 * 	0 <= nums[i] <= 50
 * 	0 <= val <= 100
 ******************************************************************************************************/

export function removeElement(nums: number[], val: number): number {
  let k = 0;
  let insertIndex = 0;
  for (let i = 0; i < nums.length; i++) {
    if (nums[i] === val) {
      k++;
    } else {
      nums[insertIndex++] = nums[i] as number;
    }
  }
  return nums.length - k;
}