Reverse Linked List

Question

Reverse a singly linked list.

Example:

Input: 1->2->3->4->5->NULL
Output: 5->4->3->2->1->NULL

LeetCodeleetcode.com/problems/reverse-linked-list

Solution

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