Rotate a linked list in Go (Golang)

Overview

The objective is to rotate a given list in the right direction by a given number of places.

Example

Input: 1->2->3->4->5
k: 2
Output: 4->5->1->2->3

Program

Here is the program for the same.

package main
import "fmt"
func main() {
first := initList()
first.AddFront(5)
first.AddFront(4)
first.AddFront(3)
first.AddFront(2)
first.AddFront(1)
first.Head.Traverse()
head := rotateRight(first.Head, 2)
fmt.Println("")
head.Traverse()
fmt.Println("")
}
func initList() *SingleList {
return &SingleList{}
}
type ListNode struct {
Val int
Next *ListNode
}
func (l *ListNode) Traverse() {
for l != nil {
fmt.Print(l.Val)
l = l.Next
}
}
type SingleList struct {
Len int
Head *ListNode
}
func (s *SingleList) Reverse() {
curr := s.Head
var prev *ListNode
var next *ListNode
for curr != nil {
next = curr.Next
curr.Next = prev
prev = curr
curr = next
}
s.Head = prev
}
func (s *SingleList) AddFront(num int) {
ele := &ListNode{
Val: num,
}
if s.Head == nil {
s.Head = ele
} else {
ele.Next = s.Head
s.Head = ele
}
s.Len++
}
func rotateRight(head *ListNode, k int) *ListNode {
if head == nil {
return nil
}
if k == 0 {
return head
}
lenList := 0
curr := head
var last *ListNode
for curr != nil {
lenList++
last = curr
curr = curr.Next
}
k = k % lenList
if k == 0 {
return head
}
curr = head
newHeadIndex := lenList - k
var prev *ListNode
for i := 0; i < newHeadIndex; i++ {
prev = curr
curr = curr.Next
}
newHeadNode := prev.Next
prev.Next = nil
last.Next = head
return newHeadNode
}

Output

12345
45123

Note: Check out our Golang Advanced Tutorial. The tutorials in this series are elaborative and we have tried to cover all concepts with examples. This tutorial is for those who are looking to gain expertise and a solid understanding of golang - Golang Advance Tutorial

Also if you are interested in understanding how all design patterns can be implemented in Golang. If yes, then this post is for you -All Design Patterns Golang