LeetCode206 reverse a singly linked list

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LeetCode206 reverse a singly linked list

Example:

输入: 1->2->3->4->5->NULL
输出: 5->4->3->2->1->NULL

Advanced:

You can reverse the iterative or recursively list. Can you solve this question in two ways?

Iteration:

public ListNode reverseList(ListNode head) {
    ListNode cur = head;
    ListNode pre = null;
    ListNode tmp = null;
    while(cur!=null){
        tmp = cur.next;
        cur.next = pre;
        pre = cur;
        cur = tmp;
    }
    return pre;
}

Recursion:

public ListNode reverseList(ListNode head) {
    if (head == null || head.next == null) {
        return head;
    }
    ListNode nextNode = head.next;
    ListNode p = reverseList(nextNode);
    nextNode.next = head;
    head.next = null;
    return p;
}