传说中的数据结构--Java

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原题链接

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {

		Scanner reader = new Scanner(System.in);
		int t,i,num,x;
		String str;
		while(reader.hasNextInt())
		{
			t=reader.nextInt();
			num=0;
			int [] array=new int[1000];
			for(i=0;i<t;i++)
			{
				str=reader.next();
				if(str.compareTo("push")==0)
				{
					x=reader.nextInt();
					array[num++]=x;
				}
				else if(str.compareTo("top")==0)
				{
					if(num==0)System.out.println("empty");
					else System.out.println(array[num-1]);
				}
				else if(str.compareTo("pop")==0)
				{
					if(num==0)System.out.println("error");
					else num--;
				}
			}
			System.out.println();
		}
		reader.close();
	}
}