2390. Removing Stars From a String

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# 題目敘述

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.

# 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.

# 解題思路

# Solution

import java.util.Stack;

class Solution {

    public String removeStars(String s) {

        char[] toChar = s.toCharArray();

        Stack<Character> stack = new Stack<>();

        for(int i = 0; i < s.length(); i++){

            if(toChar[i] == '*'){

                stack.pop();

            }else {

                stack.add(toChar[i]);

            }

        }

        String ans = "";

        while(!stack.isEmpty()){

            ans = stack.pop() + ans;

        }

        return ans;

    }

}