/*
public class ListNode {
int val;
ListNode next = null;
ListNode(int val) {
this.val = val;
}
}*/
//1.再進行逆序輸出的時候需要先儲存在head的下一節點,避免連結清單因為失去頭結點而發生錯誤 next = head.next;
//2.此時便可以開始進行逆序 将最後一個節點指向向前節點 head.next = pre;
//3.然後将向前節點後移指向頭結點 pre = head;
//4.然後将頭結點指向像一個節點進而實作了逆序 head = next;
public class Solution {
public ListNode ReverseList(ListNode head) {
if(head == null){
return null;
}
ListNode pre = null;
ListNode next = null;
while(head != null){
//經典逆序的輸出裡面的連結清單元素
next = head.next;
head.next = pre;
pre = head;
head = next;
}
return pre;
}
}