[스택] 백준 10828

 

import java.util.*;

public class Main {
	
	static List<Integer> stk = new ArrayList<Integer>();
	static int index = -1;	
	
	public static void main(String[] args) {		
		Scanner sc = new Scanner(System.in);
		StringBuffer sb = new StringBuffer();
		
		int N = sc.nextInt();
		
		for(int i = 1; i <= N; i++) {
			String cmd = sc.next();
	
			if("push".equals(cmd)) {
				push(sc.nextInt());
			} else if("pop".equals(cmd)) {
				sb.append(pop()).append("\n");
			} else if("size".equals(cmd)) {
				sb.append(size()).append("\n");
			} else if("empty".equals(cmd)) {
				sb.append(empty()).append("\n");
			} else if("top".equals(cmd)) {
				sb.append(top()).append("\n");
			} 

		}	
		System.out.println(sb.toString());
	}
	
	
	public static void push(int param) {
		stk.add(param);
		index++;
	}
	
	public static int pop() {
		if(empty() == 1) {
			return index;
		}else {
			int popItem = stk.get(index);			
			stk.remove(index);
			index--;
			return popItem;
		}
	}
	
	public static int size() {
		return stk.size();
	}
	
	public static int empty() {
		if(stk.isEmpty()) {
			return 1;
		}else {
			return 0;
		}
	}
	
	public static int top() {
		if(empty() == 1) {
			return index;
		}else {
			return stk.get(index);
		}
	}
}

StringBuffer로 해야 시간제한 통과