添加 707设计链表 Kotlin实现

problems/0707.设计链表.md

@@ -880,7 +880,72 @@ MyLinkedList.prototype.deleteAtIndex = function(index) {
  * obj.deleteAtIndex(index)
  */
 ```
+Kotlin:
+```kotlin
+class MyLinkedList {
 
+    var next: ListNode? = null
+
+    var size: Int = 0
+
+    fun get(index: Int): Int {
+        if (index + 1 > size) return -1
+        var cur = this.next
+        for (i in 0 until index) {
+            cur = cur?.next
+        }
+        return cur?.`val` ?: -1
+    }
+
+    fun addAtHead(`val`: Int) {
+        val head = ListNode(`val`)
+        head.next = this.next
+        this.next = head
+        size++
+    }
+
+    fun addAtTail(`val`: Int) {
+        val pre = ListNode(0)
+        pre.next = this.next
+        var cur: ListNode? = pre
+        while (cur?.next != null) {
+            cur = cur.next
+        }
+        cur?.next = ListNode(`val`)
+        this.next = pre.next
+        size++
+    }
+
+    fun addAtIndex(index: Int, `val`: Int) {
+        if (index == 0) return addAtHead(`val`)
+        if (index == size) return addAtTail(`val`)
+        if (index > size) return
+        var cur = this.next
+        for (i in 0 until index - 1) {
+            cur = cur?.next
+        }
+        val temp = cur?.next
+        cur?.next = ListNode(`val`)
+        cur?.next?.next = temp
+        size++
+    }
+
+    fun deleteAtIndex(index: Int) {
+        if (index + 1 > size) return
+        val pre = ListNode(0)
+        pre.next = this.next
+        var cur: ListNode? = pre
+        for (i in 0 until index) {
+            cur = cur?.next
+        }
+        val temp = cur?.next?.next
+        cur?.next?.next = null
+        cur?.next = temp
+        this.next = pre.next
+        size--
+    }
+}
+```