输入一棵二叉树，判断该二叉树是否是平衡二叉树。

 public static boolean IsBalanced_Solution(TreeNode root) {

        if(root == null){
            return true;
        }
        int left = iterTree(root.left);
        int right = iterTree(root.right);

        if(Math.abs(left-right) > 1){
            return false;
        }
        return true;
    }

    private static int iterTree(TreeNode root) {
        if(root == null){
            return 0;
        }
        int left = iterTree(root.left);
        int right = iterTree(root.right);

        return left > right ? (left+1) : (right+1);
    }