1、判断左树是否平衡，并返回左树高度
2、判断右树是否平衡，并返回右树高度
3、判断左右树高度差是否大于1，如果大于1，则不是平衡二叉树

public class TreeNode {

    public static class Node {
        private String number;
        private Node left;
        private Node right;


        public Node(String number, Node leftNode, Node rightNode) {
            this.number = number;
            this.left = leftNode;
            this.right = rightNode;
        }
    }


    public static void creadNodeNode() {
        Node Node7 = new Node("7", null, null);
        Node Node6 = new Node("6", null, null);
        Node Node5 = new Node("5", null, null);
        Node Node4 = new Node("4", null, null);
        Node Node3 = new Node("3", Node6, Node7);
        Node Node2 = new Node("2", Node4, Node5);
        Node Node1 = new Node("1", Node2, Node3);
        priIsB(Node1);

    }


    public static void priIsB(Node node) {
        boolean isB = getIsB(node).isB;
        System.out.println(isB);
    }

    /**
     * leave: 遍历到那一层
     *
     * @param node
     * @return
     */
    public static ReturnDate getIsB(Node node) {
        if (null == node) {
            return new ReturnDate(true, 0);
        }

        ReturnDate left = getIsB(node.left);
        if (!left.isB) {
            return new ReturnDate(false, 0);
        }
        ReturnDate right = getIsB(node.right);
        if (!right.isB) {
            return new ReturnDate(false, 0);
        }
        if (Math.abs(left.leave - right.leave) > 1) {
            return new ReturnDate(false, 0);
        }

        return new ReturnDate(true, Math.max(left.leave, right.leave) + 1);

    }


    public static void main(String[] args) {
        creadNodeNode();
    }

}

/**
 *
 * 返回的是否平衡信息及高度
 *
 */
class ReturnDate {
    boolean isB;
    int leave;

    public ReturnDate(boolean is, int leave) {
        this.isB = isB;
        this.leave = leave;

    }
}