07apr.txt

#include <iostream>
#include <string>
#include <algorithm>

using namespace std;

class Solution {
public:
    bool checkValidString(string s) {
        int low = 0, high = 0;
        for (char c : s) {
            low += (c == '(') ? 1 : -1;
            high += (c != ')') ? 1 : -1;
            if (high < 0) return false;
            low = max(low, 0);
        }
        return low == 0;
    }
};