g0601_0700.s0678_valid_parenthesis_string.Solution Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of leetcode-in-java21 Show documentation

Java-based LeetCode algorithm problem solutions, regularly updated

There is a newer version: 1.38

package g0601_0700.s0678_valid_parenthesis_string;

// #Medium #String #Dynamic_Programming #Greedy #Stack
// #2022_03_22_Time_0_ms_(100.00%)_Space_41.8_MB_(52.82%)

/**
 * 678 - Valid Parenthesis String\.
 *
 * Medium
 *
 * Given a string `s` containing only three types of characters: `'('`, `')'` and `'*'`, return `true` _if_ `s` _is **valid**_.
 *
 * The following rules define a **valid** string:
 *
 * *   Any left parenthesis `'('` must have a corresponding right parenthesis `')'`.
 * *   Any right parenthesis `')'` must have a corresponding left parenthesis `'('`.
 * *   Left parenthesis `'('` must go before the corresponding right parenthesis `')'`.
 * *   `'*'` could be treated as a single right parenthesis `')'` or a single left parenthesis `'('` or an empty string `""`.
 *
 * **Example 1:**
 *
 * **Input:** s = "()"
 *
 * **Output:** true
 *
 * **Example 2:**
 *
 * **Input:** s = "(\*)"
 *
 * **Output:** true
 *
 * **Example 3:**
 *
 * **Input:** s = "(\*))"
 *
 * **Output:** true
 *
 * **Constraints:**
 *
 * *   `1 <= s.length <= 100`
 * *   `s[i]` is `'('`, `')'` or `'*'`.
**/
public class Solution {
    public boolean checkValidString(String s) {
        int lo = 0;
        int hi = 0;
        for (int i = 0; i < s.length(); i++) {
            lo += s.charAt(i) == '(' ? 1 : -1;
            hi += s.charAt(i) != ')' ? 1 : -1;
            if (hi < 0) {
                break;
            }
            lo = Math.max(0, lo);
        }
        return lo == 0;
    }
}