[GeeksForGeeks] Perfect Binary Tree

Given a Binary Tree, write a function to check whether the given Binary Tree is a prefect Binary Tree or not. A Binary tree is Perfect Binary Tree in which all internal nodes have two children and all leaves are at same level.

class SubTreeInfo {
    boolean isPerfect;
    int height;
    SubTreeInfo(boolean isPerfect, int height) {
        this.isPerfect = isPerfect;
        this.height = height;
    }
}
public class PerfectBinaryTree {
    public static boolean isPerfectBt(TreeNode root) {
        return helper(root).isPerfect;
    }
    private static SubTreeInfo helper(TreeNode node) {
        SubTreeInfo info = new SubTreeInfo(true, 0);
        if(node == null) {
            return info;
        }
        SubTreeInfo leftInfo = helper(node.left);
        SubTreeInfo rightInfo = helper(node.right);
        if(leftInfo.isPerfect && rightInfo.isPerfect && leftInfo.height == rightInfo.height) {
            info.height = 1 + leftInfo.height;
        }
        else {
            info.isPerfect = false;
        }
        return info;
    }
}