LeetCode--Insertion Sort List

Sort a linked list using insertion sort.

/** * 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==NULL || head->next==NULL)return head;        ListNode* temp = head->next;ListNode* pre = head;while(temp!=NULL){if(temp->val < pre->val){head = insert(head,pre,temp);temp = pre->next;}else{    temp = temp->next;    pre = pre->next;}}return head;    }ListNode* insert(ListNode* head, ListNode* pre, ListNode* inser){ListNode* temp = head;ListNode* save = head;while(temp->val <= inser->val){save = temp;temp = temp->next;}pre->next = inser->next;inser->next = temp;if(temp == head)head = inser;elsesave->next = inser;return head;}};