【二叉树】验证满二叉树(国内定义)

给定一棵二叉树的头节点head，返回这颗二叉树是不是满二叉树

满二叉树(Full Tree):
国内定义 : 一个二叉树，如果每一个层的结点数都达到最大值，则这个二叉树就是满二叉树。也就是说，如果一个二叉树的层数为K，且结点总数是(2^k) -1 ，则它就是满二叉树。

public class 判断是否满二叉树 {
    public static class Node {
        public int value;
        public Node left;
        public Node right;

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

    public static boolean ans(Node head) {

        return process(head).isFull;
    }

    private static Info process(Node head) {
        if (head == null) {
            return new Info(0, 0, true);
        }
        Info leftInfo = process(head.left);
        Info rightInfo = process(head.right);

        int height = 0;
        int size = 0;
        boolean isFull = true;

        int leftHeight = 0;
        int leftSize = 0;
        int rightHeight = 0;
        int rightSize = 0;

        if (leftInfo != null) {
            leftHeight = leftInfo.height;
            leftSize = leftInfo.size;
            isFull = isFull && leftInfo.isFull;
        }
        if (rightInfo != null) {
            rightHeight = rightInfo.height;
            rightSize = rightInfo.size;
            isFull = isFull && rightInfo.isFull;
        }

        height = Math.max(leftHeight, rightHeight) + 1;
        size = leftSize + rightSize + 1;
        
        //1.如果左子树高度和右子树高度不同则不是满二叉树
        //2.如果 2^高度-1 和 总节点数不相等则不是满二叉树
        //"<<"比"-"优先级低 , (1 << height)加括号
        if (leftHeight != rightHeight || ((1 << height) - 1) != size){
            return new Info(height,size,false);
        }
        
        return new Info(height,size,isFull);
    }


    private static class Info {
        private int height;
        private int size;
        private boolean isFull;

        private Info(int h, int s, boolean is) {
            height = h;
            size = s;
            isFull = is;
        }
    }
}