글 읽기 - java 질문

lshsys78 2년 전 0

예제는 맞게 나오는데 어떤 문제가 있는지 궁금해요
import java.util.ArrayList;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = Integer.parseInt(sc.nextLine());
        ArrayList stack = new ArrayList<Integer>();
        int BeforeNum = 0;
        int BeforeIndex = 0;
        int IndexMinus = 0;

        for (int i = 0; i < N; i ++){
            String command = sc.nextLine();

            String[] push = command.split(" ");

            if (push[0].equals("push")){
                int pushInt = Integer.parseInt(push[1]);
                stack.add(pushInt);
                BeforeNum = pushInt;
                BeforeIndex = stack.indexOf(BeforeNum);
                IndexMinus = 0;
            }

            else if (command.equals("pop")){
                if (stack.toArray().length == 0){
                    System.out.println(-1);
                    continue;
                }
                System.out.println(BeforeNum);
                stack.remove(BeforeIndex - IndexMinus);
                BeforeNum = BeforeIndex - IndexMinus;
                IndexMinus += 1;
            }

            else if (command.equals("size")){
                System.out.println(stack.toArray().length);
            }

            else if (command.equals("empty")){
                if (stack.toArray().length == 0){
                    System.out.println(1);
                }else {
                    System.out.println(0);
                }
            }

            else if (command.equals("top")){
                if (stack.toArray().length == 0){
                    System.out.println(-1);
                }else {
                    System.out.println(BeforeNum);
                }
            }


        }


    }
}



하고  ###############################



import java.util.Scanner;
import java.util.Stack;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = Integer.parseInt(sc.nextLine());
        Stack<Integer> stack = new Stack<Integer>();
        int lastIn = 0;

        for (int i = 0; i < N; i ++){
            String strPush = sc.nextLine();
            String[] push = strPush.split(" ");

            if (push[0].equals("push")){
                int pushInt = Integer.parseInt(push[1]);
                stack.add(pushInt);
                lastIn = pushInt;
            }
            else if (strPush.equals("pop")){
                if (stack.size() == 0){
                    System.out.println(-1);
                }
                else {
                    System.out.println(lastIn);
                    stack.remove(stack.size() - 1);
                    if (stack.size() > 0){
                        lastIn = stack.lastElement();
                    }
                    else {
                        continue;
                    }
                }
            }
            else if (strPush.equals("size")){
                System.out.println(stack.size());
            }
            else if (strPush.equals("empty")){
                if (stack.size() == 0){
                    System.out.println(1);
                }else {
                    System.out.println(0);
                }
            }
            else if (strPush.equals("top")){
                if (lastIn >= 0){
                    System.out.println(lastIn);
                }else {
                    System.out.println(-1);
                }
            }
        }
    }
}
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lshsys78 2년 전 0

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