Merge pull request #3 from AdrianKuta/develop

Develop

treedatastructure/src/main/java/com/github/adriankuta/datastructure/tree/ChildDeclarationInterface.kt

@@ -0,0 +1,21 @@
+package com.github.adriankuta.datastructure.tree
+
+interface ChildDeclarationInterface<T> {
+
+    /**
+     * This method is used to easily create child in node.
+     * ```
+     * val root = treeNode("World") {
+     *     treeNode("North America") {
+     *         treeNode("USA")
+     *     }
+     *     treeNode("Europe") {
+     *         treeNode("Poland")
+     *         treeNode("Germany")
+     *     }
+     * }
+     * ```
+     */
+    @JvmSynthetic
+    fun treeNode(value: T, childDeclaration: ChildDeclaration<T>? = null)
+}

treedatastructure/src/main/java/com/github/adriankuta/datastructure/tree/Temp.java

@@ -0,0 +1,9 @@
+package com.github.adriankuta.datastructure.tree;
+
+public class Temp {
+
+    public static void main(String[] args) {
+        TreeNode<String> temp = new TreeNode<>("Test");
+
+    }
+}

treedatastructure/src/main/java/com/github/adriankuta/datastructure/tree/TreeNode.kt

@@ -1,45 +1,95 @@
 package com.github.adriankuta.datastructure.tree
 
-open class TreeNode<T>(val value: T) {
+open class TreeNode<T>(val value: T) : Iterable<TreeNode<T>>, ChildDeclarationInterface<T> {
 
-    private var parent: TreeNode<T>? = null
+    private var _parent: TreeNode<T>? = null
-    private val children = mutableListOf<TreeNode<T>>()
+    /**
+     * The converse notion of a child, an immediate ancestor.
+     */
+    val parent: TreeNode<T>?
+        get() = _parent
 
+    private val _children = mutableListOf<TreeNode<T>>()
+    /**
+     * A group of nodes with the same parent.
+     */
+    val children: List<TreeNode<T>>
+        get() = _children
+
+    /**
+     * Add new child to current node or root.
+     *
+     * @param child A node which will be directly connected to current node.
+     */
     fun addChild(child: TreeNode<T>) {
-        child.parent = this
+        child._parent = this
-        children += child
+        _children.add(child)
     }
 
+    @JvmSynthetic
+    override fun treeNode(value: T, childDeclaration: ChildDeclaration<T>?) {
+        val newChild = TreeNode(value)
+        if(childDeclaration != null)
+            newChild.childDeclaration()
+        _children.add(newChild)
+    }
+
+    /**
+     * Removes a single instance of the specified node from this tree, if it is present.
+     *
+     * @return `true` if the node has been successfully removed; `false` if it was not present in the tree.
+     */
     fun removeChild(child: TreeNode<T>): Boolean {
-        if (children.isEmpty()) {
+        val removed = child._parent?._children?.remove(child)
-            return false
+        child._parent = null
-        }
+        return removed ?: false
-
-        val nestedChildRemoved = children.map {
-            it.removeChild(child)
-        }.reduce { acc, b -> acc or b }
-
-        return children.remove(child) or nestedChildRemoved
     }
 
-    fun getParent(): TreeNode<T>? = parent
+    /**
-
+     * This function go through tree and counts children. Root element is not counted.
-    fun getChildren(): List<TreeNode<T>> = children
+     * @return All child and nested child count.
-
+     */
-    fun size(): Int {
+    fun nodeCount(): Int {
-        if (children.isEmpty())
+        if (_children.isEmpty())
             return 0
-        return children.size +
+        return _children.size +
-                children.sumBy { it.size() }
+                _children.sumBy { it.nodeCount() }
-
     }
 
-    fun depth(): Int {
+    /**
-
+     * @return The number of edges on the longest path between current node and a descendant leaf.
-        val childrenMaxDepth = children.map { it.depth() }.max() ?: 0
+     */
+    fun height(): Int {
+        val childrenMaxDepth = _children.map { it.height() }
+            .max()
+            ?: -1 // -1 because this method counts nodes, and edges are always one less then nodes.
         return childrenMaxDepth + 1
     }
 
+    /**
+     * Distance is the number of edges along the shortest path between two nodes.
+     * @return The distance between current node and the root.
+     */
+    fun depth(): Int {
+        var _depth = 0
+        var tempParent = parent
+
+        while (tempParent != null) {
+            _depth++
+            tempParent = tempParent.parent
+        }
+        return _depth
+    }
+
+    /**
+     * Remove all children from root and every node in tree.
+     */
+    fun clear() {
+        _parent = null
+        _children.forEach { it.clear() }
+        _children.clear()
+    }
+
     override fun toString(): String {
         val stringBuilder = StringBuilder()
         print(stringBuilder, "", "")
@@ -50,14 +100,36 @@ open class TreeNode<T>(val value: T) {
         stringBuilder.append(prefix)
         stringBuilder.append(value)
         stringBuilder.append('\n')
-        val childIterator = children.iterator()
+        val childIterator = _children.iterator()
         while (childIterator.hasNext()) {
             val node = childIterator.next()
-            if(childIterator.hasNext()) {
+            if (childIterator.hasNext()) {
                 node.print(stringBuilder, "$childrenPrefix├── ", "$childrenPrefix│   ")
             } else {
                 node.print(stringBuilder, "$childrenPrefix└── ", "$childrenPrefix    ")
             }
         }
     }
+
+    /**
+     * Tree is iterated by using `Pre-order Traversal Algorithm"
+     *  1. Check if the current node is empty or null.
+     *  2. Display the data part of the root (or current node).
+     *  3. Traverse the left subtree by recursively calling the pre-order function.
+     *  4. Traverse the right subtree by recursively calling the pre-order function.
+     * ```
+     * E.g.
+     *                    1
+     *                  / | \
+     *                 /  |   \
+     *               2    3     4
+     *              / \       / | \
+     *             5    6    7  8  9
+     *            /   / | \
+     *           10  11 12 13
+     *
+     * Output: 1 2 5 10 6 11 12 13 3 4 7 8 9
+     * ```
+     */
+    override fun iterator(): Iterator<TreeNode<T>> = TreeNodeIterator(this)
 }

treedatastructure/src/main/java/com/github/adriankuta/datastructure/tree/TreeNodeExt.kt

@@ -0,0 +1,17 @@
+package com.github.adriankuta.datastructure.tree
+
+typealias ChildDeclaration<T> = ChildDeclarationInterface<T>.() -> Unit
+
+/**
+ * This method can be used to initialize new tree.
+ * ```
+ * val root = treeNode("World") { ... }
+ * ```
+ * @see [ChildDeclarationInterface.treeNode]
+ */
+@JvmSynthetic
+inline fun<reified T> treeNode(value: T, childDeclaration: ChildDeclaration<T>): TreeNode<T> {
+    val treeNode = TreeNode(value)
+    treeNode.childDeclaration()
+    return treeNode
+}

treedatastructure/src/main/java/com/github/adriankuta/datastructure/tree/TreeNodeIterator.kt

@@ -0,0 +1,22 @@
+package com.github.adriankuta.datastructure.tree
+
+import java.util.*
+
+class TreeNodeIterator<T>(root: TreeNode<T>) : Iterator<TreeNode<T>> {
+
+    private val stack = Stack<TreeNode<T>>()
+
+    init {
+        stack.push(root)
+    }
+
+    override fun hasNext(): Boolean = !stack.empty()
+
+    override fun next(): TreeNode<T> {
+        val node = stack.pop()
+        node.children
+            .asReversed()
+            .forEach { stack.push(it) }
+        return node
+    }
+}

treedatastructure/src/test/java/com/github/adriankuta/datastructure/tree/TreeNodeTest.kt

@@ -0,0 +1,130 @@
+package com.github.adriankuta.datastructure.tree
+
+import org.hamcrest.CoreMatchers.`is`
+import org.hamcrest.CoreMatchers.nullValue
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertThat
+import org.junit.Test
+
+class TreeNodeTest {
+
+    @Test
+    fun removeNodeTest() {
+        val root = TreeNode<String>("Root")
+        val beveragesNode = TreeNode<String>("Beverages")
+        val curdNode = TreeNode<String>("Curd")
+        root.addChild(beveragesNode)
+        root.addChild(curdNode)
+
+        val teaNode = TreeNode<String>("tea")
+        val coffeeNode = TreeNode<String>("coffee")
+        val milkShakeNode = TreeNode<String>("Milk Shake")
+        beveragesNode.addChild(teaNode)
+        beveragesNode.addChild(coffeeNode)
+        beveragesNode.addChild(milkShakeNode)
+
+        val gingerTeaNode = TreeNode<String>("ginger tea")
+        val normalTeaNode = TreeNode<String>("normal tea")
+        teaNode.addChild(gingerTeaNode)
+        teaNode.addChild(normalTeaNode)
+
+        val yogurtNode = TreeNode<String>("yogurt")
+        val lassiNode = TreeNode<String>("lassi")
+        curdNode.addChild(yogurtNode)
+        curdNode.addChild(lassiNode)
+
+        assertEquals(
+            "Root\n" +
+                    "├── Beverages\n" +
+                    "│   ├── tea\n" +
+                    "│   │   ├── ginger tea\n" +
+                    "│   │   └── normal tea\n" +
+                    "│   ├── coffee\n" +
+                    "│   └── Milk Shake\n" +
+                    "└── Curd\n" +
+                    "    ├── yogurt\n" +
+                    "    └── lassi\n", root.toString()
+        )
+
+        System.out.println("Remove: ${curdNode.value}")
+        root.removeChild(curdNode)
+        System.out.println("Remove: ${gingerTeaNode.value}")
+        root.removeChild(gingerTeaNode)
+        assertEquals(
+            "Root\n" +
+                    "└── Beverages\n" +
+                    "    ├── tea\n" +
+                    "    │   └── normal tea\n" +
+                    "    ├── coffee\n" +
+                    "    └── Milk Shake\n", root.toString()
+        )
+    }
+
+    @Test
+    fun clearTest() {
+        val root = TreeNode<String>("Root")
+        val beveragesNode = TreeNode<String>("Beverages")
+        val curdNode = TreeNode<String>("Curd")
+        root.addChild(beveragesNode)
+        root.addChild(curdNode)
+
+        val teaNode = TreeNode<String>("tea")
+        val coffeeNode = TreeNode<String>("coffee")
+        val milkShakeNode = TreeNode<String>("Milk Shake")
+        beveragesNode.addChild(teaNode)
+        beveragesNode.addChild(coffeeNode)
+        beveragesNode.addChild(milkShakeNode)
+
+        val gingerTeaNode = TreeNode<String>("ginger tea")
+        val normalTeaNode = TreeNode<String>("normal tea")
+        teaNode.addChild(gingerTeaNode)
+        teaNode.addChild(normalTeaNode)
+
+        val yogurtNode = TreeNode<String>("yogurt")
+        val lassiNode = TreeNode<String>("lassi")
+        curdNode.addChild(yogurtNode)
+        curdNode.addChild(lassiNode)
+
+        println(root.toString())
+        println(curdNode.height())
+
+        root.clear()
+        assertThat(root.children, `is`(emptyList()))
+        assertThat(beveragesNode.children, `is`(emptyList()))
+        assertThat(curdNode.children, `is`(emptyList()))
+        assertThat(teaNode.children, `is`(emptyList()))
+        assertThat(coffeeNode.children, `is`(emptyList()))
+        assertThat(milkShakeNode.children, `is`(emptyList()))
+        assertThat(gingerTeaNode.children, `is`(emptyList()))
+        assertThat(normalTeaNode.children, `is`(emptyList()))
+        assertThat(yogurtNode.children, `is`(emptyList()))
+        assertThat(lassiNode.children, `is`(emptyList()))
+
+        assertThat(root.parent, `is`(nullValue()))
+        assertThat(beveragesNode.parent, `is`(nullValue()))
+        assertThat(curdNode.parent, `is`(nullValue()))
+        assertThat(teaNode.parent, `is`(nullValue()))
+        assertThat(coffeeNode.parent, `is`(nullValue()))
+        assertThat(milkShakeNode.parent, `is`(nullValue()))
+        assertThat(gingerTeaNode.parent, `is`(nullValue()))
+        assertThat(normalTeaNode.parent, `is`(nullValue()))
+        assertThat(yogurtNode.parent, `is`(nullValue()))
+        assertThat(lassiNode.parent, `is`(nullValue()))
+    }
+
+    @Test
+    fun kotlinExtTest() {
+        val root = treeNode("World") {
+            treeNode("North America") {
+                treeNode("USA")
+            }
+            treeNode("Europe") {
+                treeNode("Poland")
+                treeNode("Germany")
+            }
+        }
+        println(root)
+    }
+
+
+}