Update 0707-design-linked-list.kt

Author: a93a

kotlin/0707-design-linked-list.kt

@@ -1,12 +1,6 @@
 class MyLinkedList() {
-
-    class ListNode(var `val`: Int) {
-        var next: ListNode? = null
-        var prev: ListNode? = null
-    }
-
-    val head = ListNode(0)
-    val tail = ListNode(0)
+    val head = LN(0)
+    val tail = LN(0)
 
     init {
         head.next = tail
@@ -16,17 +10,18 @@ class MyLinkedList() {
     fun get(index: Int): Int {
         var current = head.next
         var i = 0
-        while( current != null && i != index) {
+        while (current != null && i != index) {
             current = current.next
             i++
         }
-        return if(current != null && current != tail) current.`val` else -1
+        
+        return if (current != null && current != tail) current.`val` else -1
     }
 
-    fun addAtHead(`val`: Int) {
+    fun addAtHead (`val`: Int) {
         val prev = head
         val next = head.next
-        val new = ListNode(`val`)
+        val new = LN(`val`)
 
         head.next = new
         new.prev = head
@@ -37,7 +32,7 @@ class MyLinkedList() {
     fun addAtTail(`val`: Int) {
         val next = tail
         val prev = tail.prev
-        val new = ListNode(`val`)
+        val new = LN(`val`)
 
         tail.prev = new
         new.prev = prev
@@ -48,13 +43,14 @@ class MyLinkedList() {
     fun addAtIndex(index: Int, `val`: Int) {
         var current = head.next
         var i = 0
-        while( current != null && i != index) {
+        while (current != null && i != index) {
             current = current.next
             i++
         }
-        if(current != null) {
+
+        if (current != null) {
             val prev = current.prev
-            val new = ListNode(`val`)
+            val new = LN(`val`)
 
             prev?.next = new
             new.prev = prev
@@ -66,27 +62,23 @@ class MyLinkedList() {
     fun deleteAtIndex(index: Int) {
         var current = head.next
         var i = 0
-        while( current != null && i != index) {
+        while (current != null && i != index) {
             current = current.next
             i++
         }
-        if(current != null && current != tail) {
+
+        if (current != null && current != tail) {
             val prev = current.prev
             val next = current.next
 
             prev?.next = next
             next?.prev = prev
         }
     }
-
 }
 
-/**
- * Your MyLinkedList object will be instantiated and called as such:
- * var obj = MyLinkedList()
- * var param_1 = obj.get(index)
- * obj.addAtHead(`val`)
- * obj.addAtTail(`val`)
- * obj.addAtIndex(index,`val`)
- * obj.deleteAtIndex(index)
- */
+class LN (
+    var `val`: Int,
+    var next: LN? = null,
+    var prev: LN? = null
+)