题解 | #反转链表#

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */
/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 * 
 * @param head ListNode类 
 * @return ListNode类
 */
struct ListNode* ReverseList(struct ListNode* head ) {
    // write code here
  //使用头插法
    struct ListNode* new_Head = (struct ListNode*)malloc(sizeof(struct ListNode));
    struct ListNode* p;
    struct ListNode* r;
    struct ListNode* s;
    p = head;
    new_Head->next = NULL;
    r = s = new_Head;
    while(p != NULL){
        s = (struct ListNode*)malloc(sizeof(struct ListNode));
        s->next = r->next;
        s->val = p->val;
        r->next = s;
        s = r;
        p = p->next;
    }
    return new_Head->next;
    

}