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| func reorderList(head *ListNode) {
if head == nil || head.Next == nil {
return
}
slow, fast := head, head
for fast != nil && fast.Next != nil {
slow = slow.Next
fast = fast.Next.Next
}
var pre *ListNode
cur := slow.Next
for cur != nil {
next := cur.Next
cur.Next = pre
pre = cur
cur = next
}
slow.Next = nil
p1, p2 := head, pre
for p2 != nil {
next1, next2 := p1.Next, p2.Next
p1.Next = p2
p2.Next = next1
p1 = next1
p2 = next2
}
}
|