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add hash table
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This commit is contained in:
Raffaele Mignone 2019-04-30 19:55:47 +02:00
parent 1bd9799816
commit 7f8273d049
Signed by: norangebit
GPG Key ID: F5255658CB220573
2 changed files with 203 additions and 0 deletions
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123
src/main/kotlin/it/norangeb/algorithms/datastructures/dictionary/HashTable.kt Normal file
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/*
* 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.Option
import arrow.core.Some
import arrow.core.toOption
class HashTable<K, V> : Dictionary<K, V> {
private val array = Array<Option<Node<K, V>>>(HASHTABLE_SIZE) { None }
private var size = 0
override fun get(key: K): Option<V> {
return get(array[getIndex(key)], key)
.map { it.value }
}
private fun get(node: Option<Node<K, V>>, key: K): Option<Node<K, V>> {
return node.flatMap {
when (key) {
it.key -> node
else -> get(it.next, key)
}
}
}
override fun set(key: K, value: V) {
val index = getIndex(key)
array[index] = set(
array[index],
key,
value
).toOption()
}
private fun set(
node: Option<Node<K, V>>,
key: K,
value: V
): Node<K, V> {
return node.fold(
{
size++
Node(key, value)
},
{
when (it.key) {
key -> it.clone(value = value)
else -> it.clone(next = set(it.next, key, value).toOption())
}
}
)
}
override fun delete(key: K) {
val index = getIndex(key)
array[index] = delete(array[index], key)
}
private fun delete(node: Option<Node<K, V>>, key: K): Option<Node<K, V>> {
return node.flatMap {
when (it.key) {
key -> {
size--
it.next
}
else -> it.clone(next = delete(it.next, key)).toOption()
}
}
}
override fun contains(key: K): Boolean = get(key) is Some
override fun isEmpty(): Boolean = size == 0
override fun size(): Int = size
private fun getIndex(key: K): Int {
return key.hashCode() % HASHTABLE_SIZE
}
data class Node<K, V>(
val key: K,
val value: V,
val next: Option<Node<K, V>> = None
) {
fun clone(
key: K = this.key,
value: V = this.value,
next: Option<Node<K, V>> = this.next
) = Node(key, value, next)
}
companion object {
const val HASHTABLE_SIZE = 40
}
}

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src/test/kotlin/it/norangeb/algorithms/datastructures/dictionary/HashTableTest.kt Normal file
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/*
* 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 be equal to`
import org.amshove.kluent.shouldEqual
import org.junit.jupiter.api.Test
class HashTableTest {
@Test
fun test() {
val map = HashTable<Int, String>()
map.size() `should be equal to` 0
map.isEmpty() `should be equal to` true
map.contains(3) `should be equal to` false
map[1] = "Zero"
map[4] = "Quattro"
map.contains(1) `should be equal to` true
map[1] shouldEqual Some("Zero")
map.size() `should be equal to` 2
map.isEmpty() `should be equal to` false
map.delete(5)
map[1] = "Uno"
map[1] shouldEqual Some("Uno")
map[41] = "41"
map[81] = "81"
map[121] = "121"
map.contains(41) `should be equal to` true
map.size() `should be equal to` 5
map[1] shouldEqual Some("Uno")
map[81] shouldEqual Some("81")
map[121] shouldEqual Some("121")
map.delete(41)
map.size() `should be equal to` 4
map.contains(41) `should be equal to` false
map.delete(121)
map.size() `should be equal to` 3
map.contains(121) `should be equal to` false
map.contains(81) `should be equal to` true
map[1] shouldEqual Some("Uno")
map[41] shouldEqual None
}
}