[JAVA] 프로그래머스 - 문자열 계산하기

https://school.programmers.co.kr/learn/courses/30/lessons/120902

프로그래머스

 

 

 

 

정답 

 

class Solution {
    public int solution(String my_string) {
        
        String arr[] = my_string.split(" "); //공백으로 구분 
        
        int answer = Integer.parseInt(arr[0]);
        for(int i=0; i<arr.length; i++)
        {
            if(arr[i].equals("+"))
            {
                answer+=Integer.parseInt(arr[i+1]);
            }
            else if(arr[i].equals("-"))
            {
                answer-=Integer.parseInt(arr[i+1]);
            }
        }
            
        return answer;
    }
}

 

 

다른 사람의 풀이 

 

 

import java.util.*;
class Solution {
    public int solution(String my_string) {
        int answer = 0;

        StringTokenizer st = new StringTokenizer(my_string);
        int length = st.countTokens();
        Stack<Integer> stack = new Stack<Integer>();
        while(st.hasMoreTokens()){
            String str = st.nextToken();
            if(stack.isEmpty()) {
                stack.push(Integer.parseInt(str));
                continue;
            }
            if(str.equals("+")){
                stack.push(stack.pop()+Integer.parseInt(st.nextToken()));
            }else if(str.equals("-")){
                stack.push(stack.pop()-Integer.parseInt(st.nextToken()));
            }
        }
        answer = stack.pop();
        return answer;
    }
}