LeetCode Sort List（链表排序）

题目链接

struct ListNode *MergeSortList(struct ListNode *head1, struct ListNode *head2){struct ListNode *p1, *p2, *p, *temp;p = (struct ListNode *)malloc(sizeof(struct ListNode));temp = p;//暂存合并后的链表的头结点p1 = head1;p2 = head2;while (p1&&p2){if (p1->val <= p2->val){p->next = p1;p1 = p1->next;}else{p->next = p2;p2 = p2->next;}p = p->next;}if (p1)p->next = p1;elsep->next = p2;p = temp->next;return p;}struct ListNode *MergeSort(struct ListNode *head){struct ListNode *fast, *slow, *slowPrev, *leftHalf, *rightHalf;fast = slow = head;if (!head || !head->next)return head;while (fast&&fast->next){fast = fast->next->next;slowPrev = slow;slow = slow->next;}slowPrev->next = NULL;leftHalf = MergeSort(head);rightHalf = MergeSort(slow);return MergeSortList(leftHalf, rightHalf);}struct ListNode *sortList(struct ListNode *head){if (!head || !head->next)return head;return MergeSort(head);//归并排序，保证算法复杂度为O(nlog(n))}