Insertion Sort List

 1 ListNode *insertionSortList( ListNode *head ) {
 2     if( !head || !head->next ) { return head; }
 3     ListNode *curr = head->next; head->next = 0;
 4     while( curr ) {
 5         ListNode *next = curr->next;
 6         if( curr->val <= head->val ) {
 7             curr->next = head;
 8             head = curr;
 9         } else {
10             ListNode *prev = head;
11             while( prev->next && prev->next->val < curr->val ) { prev = prev->next; }
12             curr->next = prev->next;
13             prev->next = curr;
14         }
15         curr = next;
16     }
17     return head;
18 }