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 withB
), whereA
andB
are valid strings, or - It can be written as
(A)
, whereA
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.
SOLUTION:
class Solution:
def minRemoveToMakeValid(self, s: str) -> str:
op = set()
n = len(s)
stack = []
for i in range(n):
if s[i] == '(':
stack.append(i)
op.add(i)
elif s[i] == ')':
if len(stack) > 0:
stack.pop()
op.add(i)
else:
op.add(i)
for i in stack:
if i in op:
op.remove(i)
return "".join(s[i] for i in sorted(op))
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