# 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 is not None: start, count = num, 0 while nums[start] is not None: temp = start start = nums[start] nums[temp] = None count += 1 result = max(result, count) return result