110. Balanced Binary Tree

class Solution {
    public boolean isBalanced(TreeNode root) {
        if (root == null) return true;
        if (Height(root) == -1) return false;
        return true;
    }
    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) return -1;
        if (Math.abs(leftHeight - rightHeight) > 1) return -1;
        return Math.max(leftHeight,rightHeight) + 1;
    }
}