The sixth day of brushing questions with force deduction

Index from 0 Start length is N Array of A, contain 0 To N - 1 All integers of . Find the largest set S And return its size , among S[i] = {A[i], A[A[i]], A[A[A[i]]], ... } And abide by the following rules .

Suppose the selection index is i The elements of A[i] by S The first element of ,S The next element of should be A[A[i]], And then A[A[A[i]]]... And so on , Keep adding until S Duplicate elements appear .

Example  1:

Input : A = [5,4,0,3,1,6,2]
Output : 4
explain : 
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}

class Solution {
    public int arrayNesting(int[] nums) {
        // Define a longest number as the return 
        int longnum = 0;
        // Loop through the ring corresponding to each subscript 
        for(int i = 0; i < nums.length; i++){
            int cont = i;
            int sum = 0;
            // Mark the accessed elements as -1 after , The starting element of the next ring is if -1
            // That means the formed ring is formed before , There is no need to calculate , Just counting is not -1 Of 
            while(nums[cont] != -1){
                sum++;
                int next = nums[cont];
                // take -1 As a mark , The accessed element is changed to -1
                nums[cont] = -1;
                cont = next;
            }
            if(longnum <= sum){
                longnum = sum;
            }
        }
        return longnum;
    }
}