Insertion Sort List

这题一开始想新建一个list，结果MLE了，后来想了想不用新建，insertion的概念理解好就行，具体编程部分不难

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode *insertionSortList(ListNode *head) {
        if (!head) return NULL;
        ListNode *hpre = new ListNode(0);
        hpre->next = head;
        ListNode *pre = head;
        head = head->next;
        while (head) {
            if (head->val > pre->val) {
                head = head->next;
                pre = pre->next;
            }
            else {
                pre->next = head->next;
                ListNode *tmp = hpre;
                while (head->val > tmp->next->val) tmp = tmp->next;
                head->next = tmp->next;
                tmp->next = head;
                head = pre->next;
            }
        }
        return hpre->next;
    }
};

 C#

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     public int val;
 *     public ListNode next;
 *     public ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode InsertionSortList(ListNode head) {
        if (head == null) return null;
        ListNode hpre = new ListNode(0);
        hpre.next = head;
        ListNode pre = head;
        head = head.next;
        while (head != null) {
            if (head.val > pre.val) {
                head = head.next;
                pre = pre.next;
            }
            else {
                pre.next = head.next;
                ListNode tmp = hpre;
                while (head.val > tmp.next.val) tmp = tmp.next;
                head.next = tmp.next;
                tmp.next = head;
                head = pre.next;
            }
        }
        return hpre.next;
    }
}