Reorder List 2020-09-16 00:21
public static void reorderList(ListNode head) {
if (head == null) {
return;
}
ListNode fast = head;
ListNode slow = head;
while (fast != null && fast.next != null) {
fast = fast.next.next;
slow = slow.next;
}
ListNode tobeReverse = slow.next;
slow.next = null;
ListNode reversedListNode = reverse(tobeReverse);
ListNode curr = head;
while (curr != null && reversedListNode != null) {
ListNode next = curr.next;
curr.next = reversedListNode;
reversedListNode = reversedListNode.next;
curr.next.next = next;
curr = next;
}
}
public static ListNode reverse(ListNode head) {
ListNode cur = head;
ListNode pre = null;
while (cur != null) {
ListNode next = cur.next;
cur.next = pre;
pre = cur;
cur = next;
}
return pre;
}
| Runtime | Memory |
|---|---|
| 1 ms | 42.7 MB |
EOF