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doubly_linked_list.go
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doubly_linked_list.go
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package main
import "fmt"
type Node struct {
Value int
Next *Node
Prev *Node
}
type DoublyLinkedList struct {
Head *Node
Tail *Node
}
func (list *DoublyLinkedList) AddLeft(value int) {
node := Node{Value: value}
if list.Head == nil {
list.Head = &node
list.Tail = &node
return
}
node.Next = list.Head
list.Head.Prev = &node
list.Head = &node
}
func (list *DoublyLinkedList) AddRight(value int) {
node := Node{Value: value}
if list.Tail == nil {
list.Tail = &node
list.Head = &node
return
}
node.Prev = list.Tail
list.Tail.Next = &node
list.Tail = &node
}
func (list *DoublyLinkedList) RemoveLeft() {
if list.Head == nil {
return
}
list.Head = list.Head.Next
if list.Head != nil {
list.Head.Prev = nil
} else {
list.Tail = nil
}
}
func (list *DoublyLinkedList) RemoveRight() {
if list.Tail == nil {
return
}
list.Tail = list.Tail.Prev
if list.Tail != nil {
list.Tail.Next = nil
} else {
list.Head = nil
}
}
func (list *DoublyLinkedList) FindAt(idx int) *Node {
pointer := list.Head
for i := 0; i < idx; i++ {
pointer = pointer.Next
if pointer == nil {
return nil
}
}
return pointer
}
func (list *DoublyLinkedList) AddAt(idx, value int) {
if idx == 0 {
list.AddLeft(value)
return
}
foundNode := list.FindAt(idx)
if foundNode == nil {
return
}
prevNode := foundNode.Prev
if prevNode == nil {
return
}
newNode := Node{Value: value}
newNode.Prev = prevNode
newNode.Next = foundNode
prevNode.Next = &newNode
foundNode.Prev = &newNode
}
func (list *DoublyLinkedList) RemoveAt(idx int) {
if idx == 0 {
list.RemoveLeft()
return
}
foundNode := list.FindAt(idx)
if foundNode == nil {
return
}
prevNode := foundNode.Prev
if prevNode == nil {
return
}
prevNode.Next = foundNode.Next
if foundNode.Next == nil {
list.Tail = prevNode
return
}
foundNode.Next.Prev = prevNode
}
func (list *DoublyLinkedList) ToSlice() []int {
var slice []int
for pointer := list.Head; pointer != nil; pointer = pointer.Next {
slice = append(slice, pointer.Value)
}
return slice
}
func main() {
list := DoublyLinkedList{}
fmt.Println("AddLeft(1, 2)")
list.AddLeft(1)
list.AddLeft(2)
fmt.Println("list.toSlice(): ", list.ToSlice())
fmt.Println("AddRight(3, 4)")
list.AddRight(3)
list.AddRight(4)
fmt.Println("list.toSlice(): ", list.ToSlice())
fmt.Println("RemoveLeft()")
list.RemoveLeft()
fmt.Println("list.toSlice(): ", list.ToSlice())
fmt.Println("RemoveRight()")
list.RemoveRight()
fmt.Println("list.toSlice(): ", list.ToSlice())
fmt.Println("AddAt(1, 5)")
list.AddAt(1, 5)
fmt.Println("list.toSlice(): ", list.ToSlice())
fmt.Println("RemoveAt(2)")
list.RemoveAt(2)
fmt.Println("list.toSlice(): ", list.ToSlice())
fmt.Println("FindAt(0)")
node := list.FindAt(0)
fmt.Println("node.Value: ", node.Value)
}