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method "count" optimized to O(1) #21

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method "count" optimized to O(1) #21

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57 changes: 27 additions & 30 deletions LinkedList/LinkedList.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -2,47 +2,38 @@
* Created by gazollajunior on 07/04/16.
*/

class Node<T>(value: T){
var value:T = value
class Node<T>(value: T) {
var value: T = value
var next: Node<T>? = null
var previous:Node<T>? = null
var previous: Node<T>? = null
}

class LinkedList<T> {

private var head:Node<T>? = null
private var head: Node<T>? = null

var isEmpty:Boolean = head == null
private var _count = 0

fun first():Node<T>? = head
var isEmpty: Boolean = head == null

fun last(): Node<T>? {
var node = head
if (node != null){
while (node?.next != null) {
node = node?.next
}
return node
} else {
return null
}
}
fun first(): Node<T>? = head

fun count():Int {
fun last(): Node<T>? {
var node = head
if (node != null){
var counter = 1
while (node?.next != null){
if (node != null) {
while (node?.next != null) {
node = node?.next
counter += 1
}
return counter
return node
} else {
return 0
return null
}
}

fun nodeAtIndex(index: Int) : Node<T>? {
val count
get() = _count

fun nodeAtIndex(index: Int): Node<T>? {
if (index >= 0) {
var node = head
var i = index
Expand All @@ -65,13 +56,15 @@ class LinkedList<T> {
} else {
head = newNode
}
_count++
}

fun removeAll() {
head = null
_count = 0
}

fun removeNode(node: Node<T>):T {
fun removeNode(node: Node<T>): T {
val prev = node.previous
val next = node.next

Expand All @@ -84,22 +77,24 @@ class LinkedList<T> {

node.previous = null
node.next = null

_count--
return node.value
}

fun removeLast() : T? {
fun removeLast(): T? {
val last = this.last()
if (last != null) {
_count--
return removeNode(last)
} else {
return null
}
}

fun removeAtIndex(index: Int):T? {
fun removeAtIndex(index: Int): T? {
val node = nodeAtIndex(index)
if (node != null) {
_count--
return removeNode(node)
} else {
return null
Expand All @@ -112,7 +107,9 @@ class LinkedList<T> {
while (node != null) {
s += "${node.value}"
node = node.next
if (node != null) { s += ", " }
if (node != null) {
s += ", "
}
}
return s + "]"
}
Expand Down