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
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