题解 | #反转链表#
反转链表
https://www.nowcoder.com/practice/75e878df47f24fdc9dc3e400ec6058ca
public ListNode ReverseList(ListNode head) { ListNode next = null; ListNode pre = null; while(head != null){ next = head.next; head.next = pre; pre = head; head = next; } return pre; }1 -> 2 -> 3 -> 4
1 <- 2 3 <- 4
每次只需要反转箭头 并保留后续代码的头部份 即next