使用队列打印出第 n 个字符串

Question

我想使用队列数据类型。

前任。

$ java NthString 5
a b c d e f
< ctrl -d >

应该给我：

b (the fifth string from the right)

这是我到目前为止所拥有的，但我不知道我的下一步：

public class NthString {
   public static void main(String[] args) {
      Queue<Integer> q = new Queue<Integer>();
      while(!StdIn.isEmpty()){
         q.enqueue(StdIn.readInt());
      }
   }
}

谢谢

Answer 1

public class NthString {
   public static void main(String[] args) {
      Integer n = Integer.parseInt(args[0]);
      Queue<Integer> q = new Queue<Integer>();
      while(!StdIn.isEmpty()){
         q.enqueue(StdIn.readInt());
      }
      while(q.size() > n){
         q.dequeue();
      }
      StdOut.println(q.peek().toString());
   }
}

Answer 2

首先，你应该知道这些东西是如何工作的，所以请仔细阅读我的评论。我已经为您编写了一个示例，但它并不完全是您需要的，但只需稍作更改即可达到要求。

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.LinkedList;
import java.util.Queue;
public class NthString {
    public static void main(String[] args) {
       // java NthString 5
       // when you run this command 5 will come from args as first parameter
       int nth = Integer.parseInt(args[0]);
       // Since we get alfabetic from console input your queue must be type of String
       Queue<String> q = new LinkedList<>();
       // This is in place of your StdIn
       BufferedReader bufferRead = new BufferedReader(new InputStreamReader(System.in));
       try {
           String s = "";
           // '/' this is the exit String that is expected from user to give at last to stop reading furthermore
           // in your case it is different, ctrl -d ?
           while (!"/".equals((s = bufferRead.readLine()))) {
               q.add(s);
           }
       } catch (IOException e) {
           e.printStackTrace();
       }
       String polled = "";
       int count = 1;
       // now you have to poll from queue back and count to get the nth string
       // since the queue is implemented as linkedlist in my case 5th element will output e instead of b
       while ((polled = q.poll()) != null) {
           if (count == nth) {
               System.out.println(nth + " th string is " + polled);
           }
           count++;
       }
   }
}