Remove the minimum number of invalid parentheses in order to make the input string valid. Return all possible results.
Note: The input string may contain letters other than the parentheses ( and ).
Example 1: Input: "()())()" Output: ["()()()", "(())()"] Example 2: Input: "(a)())()" Output: ["(a)()()", "(a())()"] Example 3: Input: ")(" Output: [""]