將從文件讀取的整數插入到鏈接列表中java

Question

我需要從文件讀入整數到鏈表中，使用插入排序對列表進行排序，然後報告我的機器花費多長時間完成插入排序使用java。目前，我的代碼除了從文件中讀取外，其它都正確，它只讀取第一個和最後一個數字。例如，如果我從相反順序的數字1到5000的文件讀取，它只會讀取和排序5000和1。

如何將文件中的所有整數讀入ListNodes？代碼貼在下面：

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，我的代碼做的一切權利，除了從 文件讀取，它只是在第一和最後一個數字讀取。例如，如果I 以相反的順序從具有數字1到5000的文件中讀取，則其 將只讀取和排序5000和1。

您實際上是從文件正確讀取所有數字。只是當您嘗試填充ListNode對象insertion時，您不會將每個節點的next指向實際的下一個節點。在您的程序中查看我的編輯。

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); 
}