add red & black BST

This commit is contained in:
Raffaele Mignone 2019-06-09 12:42:13 +02:00
parent cac5af049f
commit e8350d75dd
Signed by: norangebit
GPG Key ID: F5255658CB220573
2 changed files with 297 additions and 17 deletions

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@ -25,66 +25,182 @@
package it.norangeb.algorithms.datastructures.dictionary
import arrow.core.None
import arrow.core.Option
import arrow.core.toOption
class RedBlackBST<K : Comparable<K>, V> : OrderedDictionary<K, V> {
override fun get(key: K): Option<V> {
TODO("not implemented") // To change body of created functions use File | Settings | File Templates.
private var root: Option<Node<K, V>> = None
override fun get(key: K): Option<V> = get(root, key).map { it.value }
private fun get(
node: Option<Node<K, V>>,
key: K
): Option<Node<K, V>> = node.flatMap {
when {
key == it.key -> node
key > it.key -> get(it.right, key)
else -> get(it.left, key)
}
}
override fun set(key: K, value: V) {
TODO("not implemented") // To change body of created functions use File | Settings | File Templates.
root = set(root, key, value)
}
private fun set(
node: Option<Node<K, V>>,
key: K,
value: V
): Option<Node<K, V>> = normalize(
node.fold(
{ Node(key, value) },
{
when {
key == it.key -> it.clone(value = value)
key > it.key -> it.clone(right = set(it.right, key, value))
else -> it.clone(left = set(it.left, key, value))
}
}
)
).toOption()
private fun normalize(node: Node<K, V>): Node<K, V> {
var resultNode = node
if (isRightRed(resultNode))
resultNode = rotateLeft(resultNode)
if (isTwoRedInRow(resultNode))
resultNode = rotateRight(resultNode)
if (isBothRed(resultNode))
resultNode = colorFlip(resultNode)
return resultNode
}
private fun rotateRight(node: Node<K, V>): Node<K, V> = node
.left.fold(
{ node },
{
it.clone(
color = node.color,
right = node.clone(color = Color.RED, left = it.right).toOption()
)
}
)
private fun rotateLeft(node: Node<K, V>): Node<K, V> = node
.right.fold(
{ node },
{
it.clone(
color = node.color,
left = node.clone(color = Color.RED, right = it.left).toOption()
)
}
)
private fun colorFlip(node: Node<K, V>): Node<K, V> = node.clone(
color = Color.RED,
left = node.left.map { it.clone(color = Color.BLACK) },
right = node.right.map { it.clone(color = Color.BLACK) }
)
private fun isRightRed(node: Node<K, V>): Boolean = isRed(node.right) &&
!isRed(node.left)
private fun isTwoRedInRow(node: Node<K, V>): Boolean = isRed(node.left) &&
isRed(node.left.flatMap { it.left })
private fun isBothRed(node: Node<K, V>): Boolean = isRed(node.left) &&
isRed(node.right)
private fun isRed(node: Option<Node<K, V>>): Boolean = node
.fold(
{ false },
{ it.isRed() }
)
override fun delete(key: K) {
TODO("not implemented") // To change body of created functions use File | Settings | File Templates.
TODO("the same as bst")
}
override fun contains(key: K): Boolean {
TODO("not implemented") // To change body of created functions use File | Settings | File Templates.
TODO("the same as bst")
}
override fun isEmpty(): Boolean {
TODO("not implemented") // To change body of created functions use File | Settings | File Templates.
TODO("the same as bst")
}
override fun size(): Int {
TODO("not implemented") // To change body of created functions use File | Settings | File Templates.
TODO("the same as bst")
}
override fun max(): Option<K> {
TODO("not implemented") // To change body of created functions use File | Settings | File Templates.
TODO("the same as bst")
}
override fun min(): Option<K> {
TODO("not implemented") // To change body of created functions use File | Settings | File Templates.
TODO("the same as bst")
}
override fun floor(key: K): Option<K> {
TODO("not implemented") // To change body of created functions use File | Settings | File Templates.
TODO("the same as bst")
}
override fun ceiling(key: K): Option<K> {
TODO("not implemented") // To change body of created functions use File | Settings | File Templates.
TODO("the same as bst")
}
override fun select(pos: Int): Option<K> {
TODO("not implemented") // To change body of created functions use File | Settings | File Templates.
TODO("the same as bst")
}
override fun rank(key: K): Int {
TODO("not implemented") // To change body of created functions use File | Settings | File Templates.
TODO("the same as bst")
}
override fun <R> preOrder(transform: (K) -> R) {
TODO("not implemented") // To change body of created functions use File | Settings | File Templates.
override fun <R> preOrder(transform: (K) -> R) = preOrder(root, transform)
private fun <R> preOrder(node: Option<Node<K, V>>, transform: (K) -> R) {
node.map {
transform(it.key)
preOrder(it.left, transform)
preOrder(it.right, transform)
}
}
override fun <R> inOrder(transform: (K) -> R) {
TODO("not implemented") // To change body of created functions use File | Settings | File Templates.
TODO("the same as bst")
}
override fun <R> postOrder(transform: (K) -> R) {
TODO("not implemented") // To change body of created functions use File | Settings | File Templates.
TODO("the same as bst")
}
data class Node<K, V>(
val key: K,
val value: V,
val color: Color = Color.RED,
val left: Option<Node<K, V>> = None,
val right: Option<Node<K, V>> = None
) {
fun clone(
key: K = this.key,
value: V = this.value,
color: Color = this.color,
left: Option<Node<K, V>> = this.left,
right: Option<Node<K, V>> = this.right
): Node<K, V> = Node(key, value, color, left, right)
fun isRed() = color == Color.RED
}
enum class Color {
RED, BLACK
}
}

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@ -0,0 +1,164 @@
/*
* MIT License
*
* Copyright (c) 2019 norangebit
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*
*/
package it.norangeb.algorithms.datastructures.dictionary
import arrow.core.None
import arrow.core.Some
import org.amshove.kluent.`should equal`
import org.spekframework.spek2.Spek
import org.spekframework.spek2.style.gherkin.Feature
object RedBlackBSTTest : Spek({
Feature("red black tree") {
Scenario("get and set") {
val tree by memoized { RedBlackBST<Int, Int>() }
When("add 1, 3, 4, 6, 8 into tree") {
tree[1] = 1
tree[3] = 3
tree[4] = 4
tree[6] = 6
tree[8] = 9
}
Then("tree of 1 should equal 1") {
tree[1] `should equal` Some(1)
}
Then("tree of 2 should equal None") {
tree[2] `should equal` None
}
Then("tree of 6 should equal 6") {
tree[6] `should equal` Some(6)
}
Then("tree of 8 should equal 9") {
tree[8] `should equal` Some(9)
}
When("edit 8") {
tree[8] = 8
}
Then("tree of 8 should equal 8") {
tree[8] `should equal` Some(8)
}
}
Scenario("ordered balance") {
val tree by memoized { RedBlackBST<Int, Int>() }
Given("a 1, 2, 3, 4, 5, 6, 7 tree") {
tree[1] = 1
tree[2] = 2
tree[3] = 3
tree[4] = 4
tree[5] = 5
tree[6] = 6
tree[7] = 7
}
val result = mutableListOf<Int>()
When("compute the preOrder traverse") {
tree.preOrder { result.add(it) }
}
Then("result should equal listOf(4, 2, 1, 3, 6, 5, 7") {
result `should equal` listOf(4, 2, 1, 3, 6, 5, 7)
}
}
Scenario("reverse balance") {
val tree by memoized { RedBlackBST<Int, Int>() }
Given("a 7, 6, 5, 4, 3, 2, 1 tree") {
tree[7] = 7
tree[6] = 6
tree[5] = 5
tree[4] = 4
tree[3] = 3
tree[2] = 2
tree[1] = 1
}
val result = mutableListOf<Int>()
When("compute the preOrder traverse") {
tree.preOrder { result.add(it) }
}
Then("result should equal listOf(4, 2, 1, 3, 6, 5, 7") {
result `should equal` listOf(4, 2, 1, 3, 6, 5, 7)
}
}
Scenario("mix balance") {
val tree by memoized { RedBlackBST<Int, Int>() }
Given("a 1, 2, 3, 4, 5, 6, 7 tree") {
tree[6] = 6
tree[2] = 2
tree[4] = 4
tree[1] = 1
tree[3] = 3
tree[7] = 7
tree[5] = 5
}
val result = mutableListOf<Int>()
When("compute the preOrder traverse") {
tree.preOrder { result.add(it) }
}
Then("result should equal listOf(4, 2, 1, 3, 6, 5, 7") {
result `should equal` listOf(4, 2, 1, 3, 6, 5, 7)
}
When("add 8, 9, 10, 12, 13, 14, 15") {
tree[8] = 8
tree[9] = 9
tree[10] = 10
tree[11] = 11
tree[12] = 12
tree[13] = 13
tree[14] = 14
tree[15] = 15
}
When("compute the preOrder traverse") {
result.clear()
tree.preOrder { result.add(it) }
}
Then("result should equal listOf(8, 4, 2, 1, 3, 6, 5, 7, 12, 10, 9, 11, 14, 13, 15)") {
result `should equal` listOf(8, 4, 2, 1, 3, 6, 5, 7, 12, 10, 9, 11, 14, 13, 15)
}
}
}
})