Update CHECK COUSINS.txt

[adeebahsan1]

import java.util.ArrayList;

public class Solution {

/* Binary Tree Node class
 *
 * class BinaryTreeNode<T> {
 *     T data;
 *     BinaryTreeNode<T> left;
 *     BinaryTreeNode<T> right;
 *
 *     public BinaryTreeNode(T data) {
 *         this.data = data;
 *     }
 * }
 */

/*
    Time Complexity - O(N)
    Space Complexity - O(H)

    where N is the number of nodes in the tree
    and H is the height of the tree
*/

public static boolean areNodesSibling(BinaryTreeNode<Integer> root, int a, int b) {
    if (root == null) {
        return false;
    }

    if (root.left != null && root.right != null) {
        if (root.left.data == a && root.right.data == b) {
            return true;
        }
        if (root.left.data == b && root.right.data == a) {
            return true;
        }
    }

    if (areNodesSibling(root.left, a, b)) {
        return true;
    }
    if (areNodesSibling(root.right, a, b)) {
        return true;
    }

    return false;
}

public static int findLevel(BinaryTreeNode<Integer> root, int x, int level) {
    if (root == null) {
        return 0;
    }
    if (root.data == x) {
        return level;
    }

    // if x is found in the left subtree
    int lev = findLevel(root.left, x, level + 1);
    if (lev != 0) {
        return lev;
    }

    return findLevel(root.right, x, level + 1);
}

public static boolean isCousin(BinaryTreeNode<Integer> root, int p, int q) {
    // a and b are the given two nodes
    if (p != q && findLevel(root, p, 1) == findLevel(root, q, 1) && !areNodesSibling(root, p, q)) {
        return true;
    } else {
        return false;
    }
}

}

[adeebahsan1]

please check code