![https://leetcode.com/problems/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.
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| 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.
Example 4:
Input: s = "(a(b(c)d)"
Output: "a(b(c)d)"
|
Constraints:
- 1 <= s.length <= 10^5
- s[i] is one of ‘(’ , ‘)’ and lowercase English letters.
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| class Solution {
public String minRemoveToMakeValid(String s) {
char[] symbols = s.toCharArray();
int count = 0;
for (int i = 0; i < symbols.length; i++) {
char c = symbols[i];
if (c == '(') {
count++;
} else if (c == ')') {
if (count > 0) {
count--;
} else {
symbols[i] = '_';
}
}
}
count = 0;
for (int i = symbols.length - 1; i >= 0; i--) {
char c = symbols[i];
if (c == ')') {
count++;
} else if (c == '(') {
if (count > 0) {
count--;
} else {
symbols[i] = '_';
}
}
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < symbols.length; i++) {
if (symbols[i] != '_') {
sb.append(symbols[i]);
}
}
return sb.toString();
}
}
|
Solution 2021-11-22#
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| class Solution {
public String minRemoveToMakeValid(String s) {
char[] symbols = s.toCharArray();
int count = 0;
for (int i = 0; i < symbols.length; i++) {
if (symbols[i] == '(') {
count++;
} else if (symbols[i] == ')') {
if (count > 0) {
count--;
} else {
symbols[i] = '_';
}
}
}
count = 0;
for (int i = symbols.length - 1; i >= 0; i--) {
if (symbols[i] == ')') {
count++;
} else if (symbols[i] == '(') {
if (count > 0) {
count--;
} else {
symbols[i] = '_';
}
}
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < symbols.length; i++) {
if (symbols[i] != '_') {
sb.append(symbols[i]);
}
}
return sb.toString();
}
}
|
Solution 2022-01-22#
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| class Solution {
public String minRemoveToMakeValid(String s) {
int open = 0;
int close = 0;
char[] symbols = s.toCharArray();
for (int i = 0; i < symbols.length; i++) {
char c = symbols[i];
if (c == '(') {
open++;
} else if (c == ')') {
if (open > 0) {
open--;
} else {
symbols[i] = '_';
}
}
int j = s.length() - i - 1;
char e = symbols[j];
if (e == '(') {
if (close > 0) {
close--;
} else {
symbols[j] = '_';
}
} else if (e == ')') {
close++;
}
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < symbols.length; i++) {
if (symbols[i] != '_') {
sb.append(symbols[i]);
}
}
return sb.toString();
}
}
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