leetcode206.反转链表

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     struct ListNode *next;
 * };
 */
struct ListNode* reverseList(struct ListNode* head){
    if(head==NULL)
        return NULL;
    struct ListNode* prev=NULL;
    struct ListNode* cur=head;
    while(cur)
    {
        struct ListNode* tmp=cur->next;
        cur->next=prev;
        prev=cur;
        cur=tmp;
    }
    return prev;
}

struct ListNode* reverseList(struct ListNode* head){
    if(head==NULL||head->next==NULL)
        return head;
    struct ListNode* newHead=reverseList(head->next);
    head->next->next=head;
    head->next=NULL;
    return newHead;
}