019.go

package p019

/**
Given a linked list, remove the nth node from the end of list and return its head.

For example,

   Given linked list: 1->2->3->4->5, and n = 2.

   After removing the second node from the end, the linked list becomes 1->2->3->5.
Note:
Given n will always be valid.
Try to do this in one pass.
*/

/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */

type ListNode struct {
	Val  int
	Next *ListNode
}

func removeNthFromEnd(head *ListNode, n int) *ListNode {
	dummy := &ListNode{0, head}
	count := 0
	point := head
	for point != nil {
		count++
		point = point.Next
	}

	count = count - n
	point = dummy
	for count > 0 {
		point = point.Next
		count--
	}

	point.Next = point.Next.Next
	return dummy.Next
}