Stack and Queue

Author: DanielMichalski

src/main/kotlin/pl/dmichalski/algorithms/data_structures/_3_stack/Node.kt

@@ -0,0 +1,32 @@
+package pl.dmichalski.algorithms.data_structures._3_stack
+
+class Node(private var value: String) {
+
+    private var next: Node?
+
+    init {
+        this.next = null
+    }
+
+    fun getValue(): String {
+        return value
+    }
+
+    fun setValue(value: String) {
+        this.value = value
+    }
+
+    fun getNext(): Node? {
+        return next
+    }
+
+    fun setNext(nextNode: Node?) {
+        next = nextNode
+    }
+
+    override fun toString(): String {
+        return "Node(value='$value', next=$next)"
+    }
+
+
+}

src/main/kotlin/pl/dmichalski/algorithms/data_structures/_3_stack/Runner.kt

@@ -0,0 +1,35 @@
+package pl.dmichalski.algorithms.data_structures._3_stack
+
+object Runner {
+
+    @JvmStatic
+    fun main(args: Array<String>) {
+        println("------------------ Initial stack ------------------ ")
+        var stack = getStack()
+        printStack(stack)
+
+        println("------------------ After adding an element to the stack ------------------ ")
+        stack = getStack()
+        stack.push("before top")
+        printStack(stack)
+
+        println("------------------ After removing element from the stack ------------------ ")
+        stack = getStack()
+        stack.pop()
+        printStack(stack)
+    }
+
+    private fun getStack(): Stack {
+        val stack = Stack()
+
+        stack.push("bottom")
+        stack.push("top")
+
+        return stack
+    }
+
+    private fun printStack(stack: Stack) {
+        println(stack)
+    }
+
+}

src/main/kotlin/pl/dmichalski/algorithms/data_structures/_3_stack/Stack.kt

@@ -0,0 +1,52 @@
+package pl.dmichalski.algorithms.data_structures._3_stack
+
+import pl.dmichalski.algorithms.data_structures._1_singly_linked_list.Node
+
+class Stack {
+
+    private var first: Node?
+    private var last: Node?
+    private var size: Int
+
+    init {
+        this.first = null
+        this.last = null
+        this.size = 0
+    }
+
+    fun push(value: String): Int {
+        val newNode = Node(value)
+        if (this.first == null) {
+            this.first = newNode
+            this.last = newNode
+        } else {
+            val temp = this.first
+            this.first = newNode
+            this.last
+            this.first!!.setNext(temp)
+        }
+        return ++this.size
+    }
+
+    fun pop(): String? {
+        if (this.size == 0) {
+            return null
+        }
+
+        val temp = this.first
+
+        if (this.first == this.last) {
+            this.last = null
+        }
+        this.first = this.first!!.getNext()
+        this.size--
+        return temp!!.getValue()
+    }
+
+    override fun toString(): String {
+        return "First: $first\n" +
+                "Last: $last\n" +
+                "Size: $size\n"
+    }
+
+}

src/main/kotlin/pl/dmichalski/algorithms/data_structures/_4_queue/Node.kt

@@ -0,0 +1,32 @@
+package pl.dmichalski.algorithms.data_structures._4_queue
+
+class Node(private var value: String) {
+
+    private var next: Node?
+
+    init {
+        this.next = null
+    }
+
+    fun getValue(): String {
+        return value
+    }
+
+    fun setValue(value: String) {
+        this.value = value
+    }
+
+    fun getNext(): Node? {
+        return next
+    }
+
+    fun setNext(nextNode: Node?) {
+        next = nextNode
+    }
+
+    override fun toString(): String {
+        return "Node(value='$value', next=$next)"
+    }
+
+
+}

src/main/kotlin/pl/dmichalski/algorithms/data_structures/_4_queue/Queue.kt

@@ -0,0 +1,51 @@
+package pl.dmichalski.algorithms.data_structures._4_queue
+
+import pl.dmichalski.algorithms.data_structures._1_singly_linked_list.Node
+
+class Queue {
+
+    private var first: Node?
+    private var last: Node?
+    private var size: Int
+
+    init {
+        this.first = null
+        this.last = null
+        this.size = 0
+    }
+
+    fun enqueue(value: String): Int {
+        val newNode = Node(value)
+        if (this.first == null) {
+            this.first = newNode
+            this.last = newNode
+        } else {
+            this.last!!.setNext(newNode)
+            this.last = newNode
+        }
+        return ++this.size
+    }
+
+    fun dequeue(): String? {
+        if (this.size == 0) {
+            return null
+        }
+
+        val temp = this.first
+
+        if (this.first == this.last) {
+            this.last = null
+        }
+        this.first = this.first!!.getNext()
+        this.size--
+        return temp!!.getValue()
+    }
+
+    override fun toString(): String {
+        return "First: $first\n" +
+                "Last: $last\n" +
+                "Size: $size\n"
+    }
+
+
+}

src/main/kotlin/pl/dmichalski/algorithms/data_structures/_4_queue/Runner.kt

@@ -0,0 +1,35 @@
+package pl.dmichalski.algorithms.data_structures._4_queue
+
+object Runner {
+
+    @JvmStatic
+    fun main(args: Array<String>) {
+        println("------------------ Initial queue ------------------ ")
+        var queue = getQueue()
+        printQueue(queue)
+
+        println("------------------ After adding an element to the queue ------------------ ")
+        queue = getQueue()
+        queue.enqueue("after bottom")
+        printQueue(queue)
+
+        println("------------------ After removing element from the queue ------------------ ")
+        queue = getQueue()
+        queue.dequeue()
+        printQueue(queue)
+    }
+
+    private fun getQueue(): Queue {
+        val queue = Queue()
+
+        queue.enqueue("top")
+        queue.enqueue("bottom")
+
+        return queue
+    }
+
+    private fun printQueue(queue: Queue) {
+        println(queue)
+    }
+
+}