[심심풀이 백준문제풀기] 10828번 스택

문제 : https://www.acmicpc.net/problem/10828

import java.util.LinkedList;
import java.util.List;
import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
        Scanner scan = new  Scanner(System.in);
        InnerStack s = new InnerStack();
        int input = Integer.parseInt(scan.next());
        
        for(int i = 0 ; i < input ; i++) {
            String str = scan.next();
            if("push".equals(str)) {
                int num = Integer.parseInt(scan.next());    
                s.push(num);
            }else if("pop".equals(str)) {
                System.out.println(s.pop());
            }else if("size".equals(str)) {
                System.out.println(s.size());
            }else if("empty".equals(str)) {
                System.out.println(s.isEmpty());
            }else if("top".equals(str)) {
                System.out.println(s.top());
            }    
            
        }
    }
    
    public static class InnerStack {
        InnerStack(){
        }
        List list = new LinkedList<>();
        private int cursor = 0 ;
    
        public void push(int i ) {
            list.add(i);
            cursor++;
        }
        
        public int pop() {
            int res;
            
            if(cursor > 0) {
                res=list.get(cursor-1);
                list.remove(cursor-1);
                cursor--;
            }else {
                res = -1;
            }
            
            return res;
        }
        
        public int top() {
            int res;
            if(cursor > 0) {
                res=list.get(cursor-1);
            }else {
                res = -1;
            }
            return res;
        }
        
        public int size() {
            return cursor;
        }
        
        public int isEmpty() {
            int res;
            if (cursor ==0) {
                res = 1;
            }else {
                res = 0;
            }
            return res;
        }
        
    }
}