leetcode链接 206. 反转链表

#include <stdio.h>struct ListNode {int val;struct ListNode* next;
};
typedef struct ListNode ListNode;struct ListNode* reverseList1(struct ListNode* head) {if (head != NULL) {ListNode* n1 = NULL;ListNode* n2 = head;ListNode* n3 = n2->next;while (n2 != NULL) {n2->next = n1;n1 = n2;n2 = n3;if (n3 != NULL) {n3 = n3->next;}}return n1;}return NULL;
}ListNode* reverseList2(ListNode* head) {if (head) {ListNode* newhead = NULL;ListNode* cur = head;while (cur) {ListNode* next = cur->next;cur->next = newhead;newhead = cur;cur = next;}return newhead;}return NULL;
}