反转链表 Reverse Linked List
Reverse a singly linked list.
Example:
Input: 1->2->3->4->5->NULL
Output: 5->4->3->2->1->NULL
Follow up:
A linked list can be reversed either iteratively or recursively. Could you implement both?
思路&题解
public ListNode reverseList(ListNode head) {
ListNode pre = null;
ListNode current = head;
while(current!=null){
ListNode next = current.next;
current.next = pre;
pre = current;
current = next;
}
return pre;
}