new_contents: # Time:  O(n)
  # Space: O(1)
  
  # A zero-indexed array A consisting of N different integers is given.
  # The array contains all integers in the range [0, N - 1].
  #
  # Sets S[K] for 0 <= K < N are defined as follows:
  #
  # S[K] = { A[K], A[A[K]], A[A[A[K]]], ... }.
  #
  # Sets S[K] are finite for each K and should NOT contain duplicates.
  #
  # Write a function that given an array A consisting of N integers,
  # return the size of the largest set S[K] for this array.
  #
  # Example 1:
  # Input: A = [5,4,0,3,1,6,2]
  # Output: 4
  # Explanation: 
  # A[0] = 5, A[1] = 4, A[2] = 0, A[3] = 3, A[4] = 1, A[5] = 6, A[6] = 2.
  #
  # One of the longest S[K]:
  # S[0] = {A[0], A[5], A[6], A[2]} = {5, 6, 2, 0}
  # Note:
  # N is an integer within the range [1, 20,000].
  # The elements of A are all distinct.
  # Each element of array A is an integer within the range [0, N-1].
  
  class Solution(object):
      def arrayNesting(self, nums):
          """
          :type nums: List[int]
          :rtype: int
          """
          result = 0
          for num in nums:
              if num != None:
                  start, count = num, 0
                  while nums[start] != None:
                      temp = start
                      start = nums[start]
                      nums[temp] = None
                      count += 1
                  result = max(result, count)
          return result
   
  
subject: Create array-nesting.py