兩種方法 一種迭代 一種遞歸 都需要熟練掌握
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* struct ListNode *next;
* };
*/
struct ListNode* reverseList(struct ListNode* head) {
if(head == NULL)
return NULL;
if(head->next == NULL)
return head;
struct ListNode *node;
node = reverseList(head->next);
head->next->next = head;
head->next = NULL;
return node;
}
struct ListNode* reverseList(struct ListNode* head) {
if(head == NULL || head->next == NULL)
return head;
struct ListNode *prev, *curr, *next;
curr = head;
prev = NULL;
next = NULL;
while(curr){
next = curr->next;
curr->next = prev;
prev = curr;
curr = next;
}
return prev;
}
