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Abhishek Chaudhary
Abhishek Chaudhary

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Minimum Remove to Make Valid Parentheses

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.


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


class Solution:
    def minRemoveToMakeValid(self, s: str) -> str:
        op = set()
        n = len(s)
        stack = []
        for i in range(n):
            if s[i] == '(':
            elif s[i] == ')':
                if len(stack) > 0:
        for i in stack:
            if i in op:
        return "".join(s[i] for i in sorted(op))
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