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# 0678. Valid Parenthesis String

<https://leetcode.com/problems/valid-parenthesis-string>

## Description

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 `'*'`.

## ac

```java
```