判断是否是满二叉树

public class fullBT {

    public static class Node {
        public int value;
        public Node left;
        public Node right;

        public Node(int value) {
            this.value = value;
        }
    }


    public static class ReturnType{
        public int nodes;
        public  int height;
        public ReturnType(int nodes,int height){
            this.height=height;
            this.nodes=nodes;
        }
    }

    public static boolean isFull(Node head){
        ReturnType result= process(head);
        System.out.println(result.nodes+"--"+result.height);
        return result.nodes==Math.pow(2,result.height)-1 ;
    }

    public static ReturnType process(Node x){
        if(x==null){
            return new ReturnType(0,0);
        }
        ReturnType leftData=process(x.left);
        ReturnType rightData=process(x.right);
        int height=Math.max(leftData.height,rightData.height)+1;
        int nodes=leftData.nodes+rightData.nodes+1;
        return new ReturnType(nodes,height);

    }

    public static void main(String[] args) {
        Node head=new Node(5);
        head.left=new Node(3);
        head.right=new Node(8);
        head.left.left=new Node(2);
        head.left.right=new Node(4);
        head.left.right=new Node(4);
        head.right.left=new Node(7);
        head.right.right=new Node(9);
        Node a=null;
        System.out.println(isFull(a));


    }
}