0143-reorder-list.go

/**
 * Definition for singly-linked list.
 * type ListNode struct {
 * Val int
 * Next *ListNode
 * }
 */
funcreorderList(head*ListNode) {
slow:=head
fast:=head.Next

forfast!=nil&&fast.Next!=nil {
fast=fast.Next.Next
slow=slow.Next
 }

reversed:=reverse(slow.Next)
slow.Next=nil

curr:=head

forcurr!=nil&&reversed!=nil {
next:=curr.Next
revNext:=reversed.Next
curr.Next=reversed
reversed.Next=next
curr=next
reversed=revNext
 }
}

funcreverse(node*ListNode) *ListNode {
varprev, curr*ListNode=nil, node

forcurr!=nil {
next:=curr.Next
curr.Next=prev
prev=curr
curr=next
 }

returnprev
}