2390. Removing Stars From a String

Medium

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.

Constraints:

• 1 <= s.length <= 105

• s consists of lowercase English letters and stars *.

• The operation above can be performed on s.

解題

使用 Stack 來進行消除

func removeStars(s string) string {
    stack := make([]byte, 0)

    for i := 0; i < len(s); i++ {
        if len(stack) == 0 {
            stack = append(stack, s[i])
        } else {
            if s[i] == '*' {
                stack = stack[:len(stack)-1]
            } else {
                stack = append(stack, s[i])
            }
        }
    }

    return string(stack)
}