Check if two arrays are cyclic permutations

Question

Given two arrays, how do you check if one is a cyclic permutation of the other?

For example, given a = [1, 2, 3, 1, 5], b = [3, 1, 5, 1, 2], an

Answer 1

Here is simple adhoc approach to findout cyclic permutations with O(n) time complexity.

a = [1, 2, 3, 1, 5], b = [3, 1, 5, 1, 2]

Find index of b[0] in a[], lets say index is 'x'.Then start navigating in both the array's. a[] starts from index 'x' and b[] starts from '0'. Such that both of them must have same values. If not, they are not cyclic. Here is the sample code.

 public class CyclicPermutation {

    static char[] arr = { 'A', 'B', 'C', 'D' };
    static char[] brr = { 'C', 'D', 'K', 'B' };
    boolean dec = false;

    public static void main(String[] args) {
        boolean avail = true;
        int val = getFirstElementIndex(brr[0]);
        if(val ==Integer.MIN_VALUE){
            avail = false; 
            return;
            }

        for (int i = val, j = 0; j <= brr.length-1; ) {
            if (i > arr.length-1) {
                i = 0;
            }
            if (arr[i] == brr[j]) {
                i++;

                j++;

            } else {
                avail = false;
                System.out.println(avail);
                return;
            }


        }

   System.out.println(avail);
    }

    public static int getFirstElementIndex(char c) {

        for (int i = 0; i <= arr.length; i++) {
            if (arr[i] == c) {
                return i;
            }
        }
        return Integer.MIN_VALUE;
    }


}