Removing Stars from a String

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You are given a string s, which contains stars *.
给你一个字符串 s ，其中包含星号 * 。

In one operation, you can:
在一个操作中，您可以：

Choose a star in s.
在中 s 选择一个星号。
Remove the closest non-star character to its left, as well as remove the star itself.
删除最靠近其左侧的非星号字符，以及删除星号本身。

Return the string after all stars have been removed.
删除所有星号后返回字符串。

Note: 注意：

The input will be generated such that the operation is always possible.
将生成输入，以便操作始终是可能的。
It can be shown that the resulting string will always be unique.
可以证明，生成的字符串将始终是唯一的。

Example 1: 示例 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 "lee**t**code". s becomes "leecod*e".
The closest character to the 2nd star is 'e' in "leecode". 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: 示例 2：

Input: s = "erase*****" Output: "" Explanation: The entire string is removed, so we return an empty string.

Constraints: 约束：

1 <= s.length <= 105
s consists of lowercase English letters and stars *.
s 由小写英文字母和星星 * 组成。
The operation above can be performed on s.
上述操作可以在上 s 执行。

package org.leetcode;  
  
public class RemovingStarsFromString {  
    public static String removeStars(String s) {  
        String result = "";  
        for (int i = 0; i < s.length(); i++) {  
            if (s.charAt(i) != '*') {  
                result += s.charAt(i);  
            }  
            // if the current character is a star  
            // and the result string is not empty            // then remove the last character from the result string            else{  
                if(result.length() > 0){  
                    result = result.substring(0, result.length() - 1);  
                }  
            }  
        }  
  
        return result;  
    }  
  
  
    public static void main(String[] args) {  
        String s1 = "leet**cod*e";  
        String result1 = removeStars(s1);  
        String expected1 = "lecoe";  
        if (result1.equals(expected1)) {  
            System.out.println("Test 1 passed");  
        } else {  
            System.out.println("Test 1 failed expected: " + expected1 + " but got: " + result1);  
        }  
  
        String s2 = "erase*****";  
        String result2 = removeStars(s2);  
        String expected2 = "";  
        if (result2.equals(expected2)) {  
            System.out.println("Test 2 passed");  
        } else {  
            System.out.println("Test 2 failed expected: " + expected2 + " but got: " + result2);  
        }  
    }  
}