147. Insertion Sort List
题目
原始地址:https://leetcode.com/problems/insertion-sort-list/#/description
/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
*/
public class Solution {
public ListNode insertionSortList(ListNode head) {
}
}
描述
使用插入排序给链表排序。
分析
该题目比较考查链表基本操作。链表的插入排序不同于数组,由于不能按照index访问,所以查找插入位置时不能使用二分查找,只能从头顺序遍历。注意插入时指针的引用操作。
解法
/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
*/
public class Solution {
public ListNode insertionSortList(ListNode head) {
ListNode dummy = new ListNode(0), curr = dummy;
dummy.next = head;
while (curr.next != null) {
ListNode l = dummy;
while (l.next != curr.next && l.next.val < curr.next.val) {
l = l.next;
}
if (l != curr) {
ListNode tmp = curr.next.next;
curr.next.next = l.next;
l.next = curr.next;
curr.next = tmp;
} else {
curr = curr.next;
}
}
return dummy.next;
}
}