LeetCode 147. Insertion Sort List插入排序链表的高效简单解法

Sort a linked list using insertion sort.

 ListNode* insertionSortList(ListNode* head) {        if (!head||!head->next) return head;        ListNode preHead(0),*pre=&preHead;        preHead.next=head;        ListNode* cur = head;        while (cur) {            if (cur -> next && cur -> next -> val < cur -> val) {                while (pre -> next && pre -> next -> val < cur -> next -> val)                    pre = pre -> next;                /* Insert cur -> next after pre.*/                ListNode* temp = pre -> next;                pre -> next = cur -> next;                cur -> next = cur -> next -> next;                pre -> next -> next = temp;                // Move pre back                 pre = &preHead;            }            else cur = cur -> next;        }        return preHead.next;    }