Remove Invalid Parentheses

最新推荐文章于 2021-10-27 23:27:02 发布

原创最新推荐文章于 2021-10-27 23:27:02 发布 · 242 阅读

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public class Solution {
    int max = 0;
    public List<String> removeInvalidParentheses(String s) {
        List<String> res = new LinkedList<>();
        if (s == null) {
            return res;
        }
        helper(res, s, "", 0, 0);
        if (res.size() == 0) {
            res.add("");
        }
        return res;
    }
    
    private void helper(List<String> res, String left, String right, int leftCount, int maxCount) {
        if (left.length() == 0) {
            if (leftCount == 0 && right.length() != 0) {
                if (maxCount > max) {
                    max = maxCount;
                }
                if (maxCount == max && !res.contains(right)) {
                    res.add(right);
                    return;
                }
            }
            return;
        }
        if (left.charAt(0) == '(') {
            helper(res, left.substring(1), right + "(", leftCount + 1, maxCount + 1);
            helper(res, left.substring(1), right, leftCount, maxCount);
        } else if (left.charAt(0) == ')') {
            if (leftCount > 0) {
                helper(res, left.substring(1), right + ")", leftCount - 1, maxCount);
            }
            helper(res, left.substring(1), right, leftCount, maxCount);
        } else {
            helper(res, left.substring(1), right + left.charAt(0), leftCount, maxCount);
        }
    }
}