1249. Minimum Remove to Make Valid Parentheses

[mah-shamim]

Given a string s of '(' , ')' and lowercase English characters.

Your task is to remove the minimum number of parentheses ( '(' or ')', in any positions ) so that the resulting parentheses string is valid and return any valid string.

Formally, a parentheses string is valid if and only if:

• It is the empty string, contains only lowercase characters, or
• It can be written as AB (A concatenated with B), where A and B are valid strings, or
• It can be written as (A), where A is a valid string.

Example 1:

• Input: s = "lee(t(c)o)de)"
• Output: "lee(t(c)o)de"
• Explanation: "lee(t(co)de)" , "lee(t(c)ode)" would also be accepted.

Example 2:

• Input: s = "a)b(c)d"
• Output: "ab(c)d"

Example 3:

• Input: s = "))(("
• Output: ""
• Explanation: An empty string is also valid.

Constraints:

• 1 <= s.length <= 105
• s[i] is either'(' , ')', or lowercase English letter.