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| class Solution {
public int minAddToMakeValid(String S) {
char c1 = '(';
char c2 = ')';
Stack<Character> stack = new Stack<>();
for (int i = 0; i < S.length(); i++) {
char chr = S.charAt(i);
if (stack.empty()) {
stack.push(chr);
}else {
if (chr == c2 && stack.peek() == c1 ) {
stack.pop();
}else {
stack.push(chr);
}
}
}
return stack.size();
}
}
|
