input: Write a python function to find the smallest missing positive integer in an array.
  assert findSmallestMissingPositiveInteger([1, 10, 5, 3, 8]) == 2
  assert findSmallestMissingPositiveInteger([3, 4, -1, 1]) == 2
  assert findSmallestMissingPositiveInteger([7, 8, 9, 11, 12]) == 1
  assert findSmallestMissingPositiveInteger([1, 2, 0]) == 3
output: def findSmallestMissingPositiveInteger(nums):
      nums = [num for num in nums if num > 0]
      nums_set = set(nums)
      smallest_missing = 1
  
      while smallest_missing in nums_set:
          smallest_missing += 1
  
      return smallest_missing