#1249

Minimum Remove to Make Valid Parentheses

pupil · 535 · lc medium +28 · verified · 71.3% accepted · 7,374 likes · top 80%

⚑ Monotonic Stack⚑ Bracket / Parentheses Matching

Description

You are given a string s containing '(', ')', and lowercase English letters. Remove the fewest parentheses possible so that the remaining string has a valid parenthesis structure, and return any valid result.

A parenthesis string is valid if and only if:

 - It is empty or contains only lowercase letters, or

 - It can be written as AB where A and B are both valid, or

 - It can be written as (A) where A is valid.

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.

Code

1
2
3