백준 Java 10828번 : 스택

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

10828번: 스택

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import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;
import java.util.Stack;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		Stack st = new Stack();
		int a = Integer.parseInt(br.readLine());
		
		for(int i = 0; i < a; i++) {
			String b = br.readLine();
			if(b.contains("push")) {
				String num[] = b.split(" ");
				st.push(Integer.parseInt(num[1]));
			} else if(b.equals("pop")) {
				System.out.println(st.isEmpty()?-1:st.pop());
			} else if(b.equals("size")) {
				System.out.println(st.size());
			} else if(b.equals("empty")) {
				System.out.println(st.isEmpty()?1:0);
			} else if(b.equals("top")) {
				System.out.println(st.isEmpty()?-1:st.peek());
			}
		}
	}
}