C语言 | Leetcode C语言题解之第143题重排链表

题目：

题解：

struct ListNode* middleNode(struct ListNode* head) {struct ListNode* slow = head;struct ListNode* fast = head;while (fast->next != NULL && fast->next->next != NULL) {slow = slow->next;fast = fast->next->next;}return slow;
}struct ListNode* reverseList(struct ListNode* head) {struct ListNode* prev = NULL;struct ListNode* curr = head;while (curr != NULL) {struct ListNode* nextTemp = curr->next;curr->next = prev;prev = curr;curr = nextTemp;}return prev;
}void mergeList(struct ListNode* l1, struct ListNode* l2) {struct ListNode* l1_tmp;struct ListNode* l2_tmp;while (l1 != NULL && l2 != NULL) {l1_tmp = l1->next;l2_tmp = l2->next;l1->next = l2;l1 = l1_tmp;l2->next = l1;l2 = l2_tmp;}
}void reorderList(struct ListNode* head) {if (head == NULL) {return;}struct ListNode* mid = middleNode(head);struct ListNode* l1 = head;struct ListNode* l2 = mid->next;mid->next = NULL;l2 = reverseList(l2);mergeList(l1, l2);
}