Delete all nodes whose node digit sum is odd from circular linked list in golang

Go program for Delete all nodes whose node digit sum is odd from circular linked list. Here more information.

package main
import "fmt"
// Go Program
// Remove all the Odd digit sum nodes from a circular linked list
type LinkNode struct {
	data int
	next * LinkNode
}
func getLinkNode(data int) * LinkNode {
	// return new LinkNode
	return &LinkNode {
		data,
		nil,
	}
}
type CircularLinkedList struct {
	head * LinkNode
	tail * LinkNode
}
func getCircularLinkedList() * CircularLinkedList {
	// return new CircularLinkedList
	return &CircularLinkedList {
		nil,
		nil,
	}
}
//Add node at the end position efficiently
func(this *CircularLinkedList) insert(value int) {
	// Create a new node
	var node * LinkNode = getLinkNode(value)
	if this.head == nil {
		// When first node
		this.head = node
	} else {
		// Connect new node at the last
		this.tail.next = node
	}
	// Connect last node to first node
	node.next = this.head
	// Set new last node
	this.tail = node
}
// Display node element of circular linked list
func(this CircularLinkedList) display() {
	if this.head == nil {
		fmt.Println("\n Empty Linked List")
	} else {
		// First node of linked list
		fmt.Print("  ", this.head.data)
		var temp * LinkNode = this.head.next
		// Display linked list node
		for (temp != nil && temp != this.head) {
			// Display node value
			fmt.Print("  ", temp.data)
			// visit to next node
			temp = temp.next
		}
	}
}
// Sum of digits
func(this CircularLinkedList) digitSum(num int) int {
	var n int = num
	var sum int = 0
	if n < 0 {
		// When node value is negative
		n = -n
	}
	for (n > 0) {
		sum += (n % 10)
		n = n / 10
	}
	return sum
}
func(this *CircularLinkedList) removeOddDigitSumNode() {
	if this.head == nil {
		return
	}
	var temp * LinkNode = this.head
	var auxiliary * LinkNode = this.head
	var point * LinkNode = nil
	for (temp != nil) {
		if (this.digitSum(temp.data) % 2) != 0 {
			auxiliary = temp
			temp = temp.next
			if auxiliary == this.head {
				// Enter to remove first node
				if auxiliary == this.tail {
					// Enter to removing single node
					this.tail = nil
					this.head = nil
					temp = nil
					point = nil
				} else {
					this.head = temp
					this.tail.next = temp
				}
			} else if auxiliary == this.tail {
				// When Remove last node
				if point != nil {
					point.next = this.head
				}
				this.tail = point
			} else {
				// When removing intermediate node
				if point != nil {
					point.next = temp
				}
			}
			auxiliary = nil
		} else {
			point = temp
			// Visit to next node
			temp = temp.next
			if temp == this.head {
				// Stop the process
				temp = nil
			}
		}
	}
}
func main() {
	var cll * CircularLinkedList = getCircularLinkedList()
	// Insert node
	cll.insert(131)
	cll.insert(12)
	cll.insert(33)
	cll.insert(10)
	cll.insert(143)
	cll.insert(91)
	cll.insert(27)
	cll.insert(125)
	cll.insert(89)
	fmt.Println("\n Before remove odd digit sum nodes")
	cll.display()
	/*
	    Node   Digit Sum    Odd
	    ----- -----------  --------
	    131   [1+3+1] 5     Yes
	    12    [1+2]   3     Yes
	    33    [3+3]   6     No
	    10    [10]    1     Yes
	    143   [1+4+3] 8     No
	    91    [9+1]   10    No
	    27    [2+7]   9     Yes        
	    125   [1+2+5] 8     No
	    89    [8+9]   17    Yes
	    --------------------------
	    Result 
	    ------
	    33 → 143 → 91 → 125 ┐ 
	     └-----------------⤶
	        
	*/
	cll.removeOddDigitSumNode()
	fmt.Println("\n After remove odd digit sum nodes")
	cll.display()
}

Output

 Before remove odd digit sum nodes
 131  12  33  10  143  91  27  125  89
 After remove odd digit sum nodes
 33  143  91  125