백준 10828 자바

스택을 구현하는 문제이다.스택 또한 자바에서 제공한다.

import java.util.Stack;
import java.util.StringTokenizer;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;




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));
     Stack<Integer> stack = new Stack<>();
     int N = Integer.parseInt(br.readLine());

     
     for(int i=0;i<N;i++){
         String str = br.readLine();
         if(str.contains(" ")){
            StringTokenizer st = new StringTokenizer(str," ");
            String[] arr = new String[2];
            arr[0] = st.nextToken();
            arr[1] = st.nextToken();
            
            stack.push(Integer.parseInt(arr[1]));
         }else{
            switch(str){
                case "pop":
                    if(stack.empty()==true){
                        System.out.println(-1);
                        break;
                    }
                    else{
                        System.out.println(stack.pop());
                        break;
                    }
                case "size":
                    System.out.println(stack.size());
                    break;
                case "empty":
                    if(stack.empty()==true){
                        System.out.println(1);
                        break;
                    }else{
                        System.out.println(0);
                        break;
                    }
                case "top":
                    if(stack.empty()==true){
                        System.out.println(-1);
                        break;
                    }else{
                        System.out.println(stack.peek());
                        break;
                    }
            }
         }
     }
    }

}

딱히 어려운건 없었다.