将从文件读取的整数插入到链接列表中java

Question

我需要从文件读入整数到链表中，使用插入排序对列表进行排序，然后报告我的机器花费多长时间完成插入排序使用java。目前，我的代码除了从文件中读取外，其它都正确，它只读取第一个和最后一个数字。例如，如果我从相反顺序的数字1到5000的文件读取，它只会读取和排序5000和1。

如何将文件中的所有整数读入ListNodes？代码贴在下面：

import java.io.File; 
import java.io.FileNotFoundException; 
import java.util.*; 

class ListNode { 
    int val; 
    ListNode next; 

    ListNode(int x) { 
     val = x; 
     next = null; 
    } 
} 

public class InsertionLinkedList { 

    public static ListNode insertionSortList(ListNode head) { 

     long start = System.nanoTime(); 
     if (head == null || head.next == null) 
      return head; 

     ListNode newHead = new ListNode(head.val); 
     ListNode pointer = head.next; 

     // loop through each element in the list 
     while (pointer != null) { 
      // insert this element to the new list 

      ListNode innerPointer = newHead; 
      ListNode next = pointer.next; 

      if (pointer.val <= newHead.val) { 
       ListNode oldHead = newHead; 
       newHead = pointer; 
       newHead.next = oldHead; 
      } else { 
       while (innerPointer.next != null) { 

        if (pointer.val > innerPointer.val && pointer.val <= innerPointer.next.val) { 
         ListNode oldNext = innerPointer.next; 
         innerPointer.next = pointer; 
         pointer.next = oldNext; 
        } 

        innerPointer = innerPointer.next; 
       } 

       if (innerPointer.next == null && pointer.val > innerPointer.val) { 
        innerPointer.next = pointer; 
        pointer.next = null; 
       } 
      } 

      // finally 
      pointer = next; 
     } 
     long time = System.nanoTime() - start; 
     System.out.printf("The time taken was %.1f ns%n", (double) time); 
     return newHead; 
    } 

    public static void main(String[] args) throws FileNotFoundException { 

     Scanner scanner = new Scanner(new File("random5k.txt")); 
     ListNode insertion = new ListNode(scanner.nextInt()); 
     while(scanner.hasNextInt()){ 
      ListNode nextNode = new ListNode(scanner.nextInt()); 
      insertion.next = nextNode; 
     } 

     insertion = insertionSortList(insertion); 
    } 
} 

Answer 1

目前，我的代码做的一切权利，除了从 文件读取，它只是在第一和最后一个数字读取。例如，如果I 以相反的顺序从具有数字1到5000的文件中读取，则其 将只读取和排序5000和1。

您实际上是从文件正确读取所有数字。只是当您尝试填充ListNode对象insertion时，您不会将每个节点的next指向实际的下一个节点。在您的程序中查看我的编辑。

public static void main(String[] args) throws FileNotFoundException { 

Scanner scanner = new Scanner(new File("random5k.txt")); 
ListNode insertion = new ListNode(scanner.nextInt()); 
ListNode intNodes = insertion; 
while(scanner.hasNextInt()){ 
    ListNode nextNode = new ListNode(scanner.nextInt()); 
    insertion.next = nextNode; 
    insertion = nextNode; 
} 
intNodes = insertionSortList(intNodes); 
}