Insertion Sort List

使用插入排序对链表进行排序

最新推荐文章于 2024-11-10 21:15:35 发布

cgdong2014

最新推荐文章于 2024-11-10 21:15:35 发布

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分类专栏： LeetCode LinkedList

本文链接：https://blog.youkuaiyun.com/cgdong2014/article/details/39393421

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本文介绍了一种使用插入排序算法对链表进行排序的方法。首先创建一个头节点和两个指针，一个用于遍历链表，另一个用于比较当前节点的值。通过循环比较并插入节点，确保链表有序。注意在插入操作后更新指针位置。

Sort a linked list using insertion sort.

1. Create a new head and keep two pointer which are pre pointer and current pointer.

2. Each nodes need to be compared to the current node to find a node's value bigger than this node.

3. insert this node between pre and cur node.

易错点：在插完之后，必须要把pre 和 cur 指针指到最前

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    public ListNode insertionSortList(ListNode head) {
        ListNode newHead = new ListNode(Integer.MIN_VALUE);
        ListNode pre = newHead;
        ListNode cur = newHead.next;
        while(head != null){
            while(cur != null && cur.val < head.val){
                pre = cur;
                cur = cur.next;
            }
            ListNode insertNode = head;
            head = head.next;
            pre.next = insertNode;
            insertNode.next = cur;
            pre = newHead;
            cur = newHead.next;
        }
        return newHead.next;
    }
}