- 删除无效的括号
有趣的困难题，难点在于题目的理解，为了加深记忆，所以用python 和 JAVA写了两遍，其实也可用用记忆化提升速度
中间关于java中的转换有点忘记了，特地记录一下：
Java Array、List、Set互相转化
class Solution {
private Set res = new HashSet<>();
String s;
public List removeInvalidParentheses(String _s) {
s = _s;
int leftRemove =0, rightRemove =0,stack=0;
for (char c : s.toCharArray()){
if (c == '(') leftRemove++;
else if (c==')'){
if (leftRemove==0) rightRemove++;
else leftRemove--;
}
}
dfs(0,"",leftRemove,rightRemove,stack);
return new ArrayList<>(res);
}
private void dfs(int idx,String curStr, int left, int right,int stack){
if (stack<0 || left<0 || right<0|| s.length()-idx
python版本
class Solution:
def removeInvalidParentheses(self, s: str) -> List[str]:
cnt = 0
stack=[]
for i in range(len(s)):
if s[i] == '(':
stack.append(i)
elif s[i]==')':
if not stack:
cnt+=1
else:
stack.pop()
newli=[]
leftcnt = len(stack)
newli=list(s)
res=set()
def dfs(li,curs,lcnt,cnt,stack):
if stack<0 or lcnt<0 or cnt<0 or len(li) 
