88 lines
2.8 KiB
Kotlin
88 lines
2.8 KiB
Kotlin
/*
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* MIT License
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*
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* Copyright (c) 2019 norangebit
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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*/
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package it.norangeb.algorithms.sorting
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object Mergesort : Sorter {
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override fun <T : Comparable<T>> sort(array: Array<T>) {
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sort(array) { t1, t2 -> t1 < t2 }
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}
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override fun <T, C : Comparable<C>> sortBy(array: Array<T>, compareBy: (T) -> C) {
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sort(array) { t1, t2 -> compareBy(t1) < compareBy(t2) }
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}
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override fun <T> sortWith(array: Array<T>, compare: (T, T) -> Int) {
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sort(array) { t1, t2 -> compare(t1, t2) < 0 }
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}
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private fun <T> sort(array: Array<T>, isLess: (T, T) -> Boolean) {
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val auxiliary = arrayOfNulls<Any>(array.size) as Array<T>
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sort(array, auxiliary, 0, array.size - 1, isLess)
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}
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private fun <T> sort(
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array: Array<T>,
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auxiliary: Array<T>,
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low: Int,
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high: Int,
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isLess: (T, T) -> Boolean
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) {
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if (high <= low) return
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val mid = low + (high - low) / 2
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sort(array, auxiliary, low, mid, isLess)
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sort(array, auxiliary, mid + 1, high, isLess)
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if (!isLess(array[mid+1], array[mid]))
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return
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merge(array, auxiliary, low, mid, high, isLess)
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}
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private inline fun <T> merge(
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array: Array<T>,
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auxiliary: Array<T>,
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low: Int,
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mid: Int,
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high: Int,
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isLess: (T, T) -> Boolean
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) {
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for (i in low..high)
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auxiliary[i] = array[i]
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var i = low
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var j = mid + 1
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for (k in low..high)
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when {
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i > mid -> array[k] = auxiliary[j++]
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j > high -> array[k] = auxiliary[i++]
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isLess(auxiliary[j], auxiliary[i]) -> array[k] = auxiliary[j++]
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else -> array[k] = auxiliary[i++]
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}
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}
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} |