[nim4leetcode] 27. remove element

Problem

Given an array and a value, remove all instances of that value in-place and return the new length.

Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.

The order of elements can be changed. It doesn’t matter what you leave beyond the new length.

Example:

Given nums = [3,2,2,3], val = 3,

Your function should return length = 2, with the first two elements of nums being 2.

Solution

proc removeElement(nums: var seq[int], val: int): int =
  var n = 0
  for i in 0 ..< nums.len:
    if nums[i] != val:
      nums[n] = nums[i]
      n += 1
  result = n

when isMainModule:
  var nums = @[3, 2, 2, 3]
  assert removeElement(nums, 3) == 2
  assert nums[0] == 2 and nums[1] == 2