2390.Removing Stars From a String
===
###### tags: `Medium`,`String`,`Stack`
[2390. Removing Stars From a String](https://leetcode.com/problems/removing-stars-from-a-string/)
### 題目描述
You are given a string `s`, which contains stars `*`.
In one operation, you can:
* Choose a star in `s`.
* Remove the closest **non-star** character to its **left**, as well as remove the star itself.
Return *the string after **all** stars have been removed.*
**Note:**
* The input will be generated such that the operation is always possible.
* It can be shown that the resulting string will always be unique.
### 範例
**Example 1:**
```
Input: s = "leet**cod*e"
Output: "lecoe"
Explanation: Performing the removals from left to right:
- The closest character to the 1st star is 't' in "leet**cod*e". s becomes "lee*cod*e".
- The closest character to the 2nd star is 'e' in "lee*cod*e". s becomes "lecod*e".
- The closest character to the 3rd star is 'd' in "lecod*e". s becomes "lecoe".
There are no more stars, so we return "lecoe".
```
**Example 2:**
```
Input: s = "erase*****"
Output: ""
Explanation: The entire string is removed, so we return an empty string.
```
**Constraints**:
* 1 <= `s.length` <= 10^5^
* `s` consists of lowercase English letters and stars `*`.
* The operation above can be performed on `s`.
### 解答
#### Python
```python=
class Solution:
def removeStars(self, s: str) -> str:
stack = []
for ch in s:
if ch != '*':
stack.append(ch)
else:
stack.pop()
return "".join(stack)
```
> [name=Ron Chen][time=Tue, Apr 11, 2023]
```python=
class Solution:
def removeStars(self, s: str) -> str:
new_s = []
for i in range(s):
if i != '*':
new_s.append(i)
else:
new_s.pop()
ret = ''.join(new_s)
return ret
```
> [name=gp][time=Tue, Apr 11, 2023]
#### Javascript
```javascript=
function removeStars(s) {
const stack = [];
for (const c of s) {
if (c !== '*') {
stack.push(c);
} else {
stack.pop();
}
}
return stack.join('');
}
```
> [name=Marsgoat][time=Tue, Apr 11, 2023]
#### C#
```csharp=
public string RemoveStars(string s) {
char[] output = new char[s.Length];
int len = 0;
for (int i = 0; i < s.Length; i++) {
output[len] = s[i];
len = s[i] switch {
'*' => len - 1,
_ => len + 1
};
}
return string.Concat(output.Take(len));
}
```
> [name=Jim][time=Wed, Apr 12, 2023]
### Reference
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