function removeDuplicates(nums: number[]): number {
  let count = 0;

  for (let i = 0; i < nums.length; i++) {
    // skip already registered number
    if (i < nums.length - 1 && nums[i] == nums[i + 1]) {
      continue;
    }

    // register number
    nums[count] = nums[i];
    // increment total
    count++;
  }

  return count;
}