1678. Goal Parser Interpretation

package LeetCode_1678

/**
 * 1678. Goal Parser Interpretation
 * https://leetcode.com/problems/goal-parser-interpretation/
 * You own a Goal Parser that can interpret a string command.
 * The command consists of an alphabet of "G", "()" and/or "(al)" in some order.
 * The Goal Parser will interpret "G" as the string "G", "()" as the string "o", and "(al)" as the string "al".
 * The interpreted strings are then concatenated in the original order.
Given the string command, return the Goal Parser's interpretation of command.

Example 1:
Input: command = "G()(al)"
Output: "Goal"
Explanation: The Goal Parser interprets the command as follows:
G -> G
() -> o
(al) -> al
The final concatenated result is "Goal".

Example 2:
Input: command = "G()()()()(al)"
Output: "Gooooal"

Example 3:
Input: command = "(al)G(al)()()G"
Output: "alGalooG"

Constraints:
1. 1 <= command.length <= 100
2. command consists of "G", "()", and/or "(al)" in some order.
 * */
class Solution {
    /*
    * solution: scan command, Time:O(n), Space:O(n)
    * */
    fun interpret(command: String): String {
        val sb = StringBuilder()
        var i = 0
        val n = command.length
        while (i < n) {
            if (command[i] == 'G') {
                sb.append("G")
            } else if (i + 1 < n && command[i + 1] == ')') {
                sb.append("o")
                i++
            } else {
                sb.append("al")
                i += 3
            }
            i++
        }
        return sb.toString()
    }
}