Reverse a singly linked list

Reverse a singly linked list

Description

Given a linked list, remove the n-th node from the end of list and return its head.

Example1:

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

Tags: LinkedList

解讀題意

翻轉單向鏈表

思路1

1. 保存head下一節點
2. 將head所指向的下一節點改爲prev
3. prev替換爲head
4. 將第一步保存的下一節點替換爲head，用於下次循環

class Solution { 

        public ListNode reverseList(ListNode head) {
                ListNode prev = null;
                ListNode curr = head;
                while (curr != null) {
                    ListNode temp = curr.next;
                    curr.next = prev;
                    prev = curr;
                    curr = temp;
                }
                // fix head
                head = prev;

                return head; 
        }
}

leetCode彙總：https://blog.csdn.net/qingtian_1993/article/details/80588941

項目源碼，歡迎star：https://github.com/mcrwayfun/java-leet-code