题解 | #牛群分隔#

链表的拆分与合并。为了合并的方便，引入了伪头指针。

package main
import "fmt"
import . "nc_tools"
/*
 * type ListNode struct{
 *   Val int
 *   Next *ListNode
 * }
 */
func cow_partition( head *ListNode ,  x int ) *ListNode {
    if head == nil{
        fmt.Println()
        return head
    }
    pHead1, pHead2 := &ListNode{Next: head}, &ListNode{}
    prev, curr, curr2 := pHead1, head, pHead2
    for curr != nil{
        if curr.Val < x{
            prev.Next = curr.Next
            curr2.Next = curr
            curr = curr.Next
            curr2 = curr2.Next
            curr2.Next = nil
        }else{
            prev, curr = curr, curr.Next
        }
    }
    curr2.Next = pHead1.Next
    return pHead2.Next
}