3612. Process String with Special Operations I

class Solution {
    public String processStr(String s) {
        StringBuilder result = new StringBuilder();

        for (char ch : s.toCharArray()) {

            if (ch >= 'a' && ch <= 'z') {
                result.append(ch);
            }
            else if (ch == '*') {
                if (result.length() > 0) {
                    result.deleteCharAt(result.length() - 1);
                }
            }
            else if (ch == '#') {
                result.append(result.toString());
            }
            else if (ch == '%') {
                result.reverse();
            }
        }

        return result.toString();
    }
}

class Solution:
    def processStr(self, s: str) -> str:
        result = []

        for ch in s:
            if 'a' <= ch <= 'z':
                result.append(ch)
            elif ch == '*':
                if result:
                    result.pop()
            elif ch == '#':
                result.extend(result)
            elif ch == '%':
                result.reverse()

        return "".join(result)

class Solution {
public:
    string processStr(string s) {

        string result;

        for (char ch : s) {

            if (ch >= 'a' && ch <= 'z') {
                result.push_back(ch);
            }
            else if (ch == '*') {
                if (!result.empty())
                    result.pop_back();
            }
            else if (ch == '#') {
                result += result;
            }
            else if (ch == '%') {
                reverse(result.begin(), result.end());
            }
        }

        return result;
    }
};

var processStr = function(s) {

    let result = [];

    for (let ch of s) {

        if (ch >= 'a' && ch <= 'z') {
            result.push(ch);
        }
        else if (ch === '*') {
            if (result.length)
                result.pop();
        }
        else if (ch === '#') {
            result.push(...result);
        }
        else if (ch === '%') {
            result.reverse();
        }
    }

    return result.join('');
};