class Solution {
    public boolean isBalanced(TreeNode root) {
        return height(root) >= 0;
    }

    public int height(TreeNode root) {
        if (root == null) {
            return 0;
        }
        int leftHeight = height(root.left);
        int rightHeight = height(root.right);
        if (leftHeight == -1 || rightHeight == -1 || Math.abs(leftHeight - rightHeight) > 1) {
            return -1;
        } else {
            return Math.max(leftHeight, rightHeight) + 1;
        }
    }

}




//代码二
class Solution {
    public boolean isBalanced(TreeNode root) {
        return height(root) >= 0;
    }
    private int height(TreeNode root){
        if(root == null) return 0;
        int left = height(root.left);
        int right = height(root.right);
        return (left == -1 || right == -1 || Math.abs(height(root.left) - height(root.right)) > 1) ? -1 : Math.max(left, right) + 1;
    }
}

老师，
代码一 提交给Leetcode运行时间1Ms. 代码二 的则是26Ms.

为什么会有这种现象出现呀？ 我找不出有啥不同呢。