엘리스 알고리즘 코드 챌린지 Day3(07월 10일) - Java

나의 제출

import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        String S = br.readLine();
        char[] arr = S.toCharArray();

        Stack<Character> stack = new Stack<>();
        int closeCnt = 0;
        for (int i=0; i<arr.length; i++) {
            if (Character.isDigit(arr[i])) {
                if (i+1 < arr.length && arr[i+1] == '(') {
                    stack.push(arr[i]);
                } else {
                    if (closeCnt > 0) {
                        stack.add(stack.size() - 1 - closeCnt, 'c');
                        closeCnt = 0;
                    } else {
                        stack.push('c');
                    }
                }
            } else {
                if (arr[i] == ')') {
                    closeCnt++;
                }
            }
        }

        int length = 0;
        while (!stack.isEmpty()) {
            Character ch = stack.pop();
            if (ch == 'c') {
                length++;
            } else {
                length *= Character.getNumericValue(ch);
            }
        }

        bw.write(Integer.toString(length));
        bw.flush();
        bw.close();
    }
}