implement prefix average in recursive way
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@ -6,7 +6,7 @@
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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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* to use, copy, modify, tryMerge, 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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@ -25,19 +25,29 @@
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package it.norangeb.algorithms.exercises
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class PrefixAverage {
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companion object {
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fun prefixAverage(arrayIn: IntArray): IntArray {
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object PrefixAverage {
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fun prefixAverage(arrayIn: IntArray): IntArray {
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val arrayOut = IntArray(arrayIn.size)
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var currentSum = 0
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val arrayOut = IntArray(arrayIn.size)
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var currentSum = 0
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for (i in 0 until arrayIn.size) {
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currentSum += arrayIn[i]
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arrayOut[i] = currentSum / (i + 1)
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for (i in 0 until arrayIn.size) {
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currentSum += arrayIn[i]
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arrayOut[i] = currentSum / (i + 1)
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}
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return arrayOut
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}
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fun recursivePrefixAverage(arrayIn: IntArray, position: Int = 0, acc: Int = 0): IntArray {
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return when (position) {
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arrayIn.size -> IntArray(arrayIn.size)
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else -> {
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val newAcc = arrayIn[position] + acc
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val array = recursivePrefixAverage(arrayIn, position + 1, newAcc)
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array[position] = newAcc / (position + 1)
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array
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}
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return arrayOut
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}
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}
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}
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}
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@ -67,4 +67,42 @@ class PrefixAverageTest {
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arrayOut `should equal` intArrayOf(21, 21, 21, 21, 21)
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}
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@Test
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fun testNominalCaseRecursive() {
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val arrayIn = intArrayOf(21, 23, 25, 31, 20, 18, 16)
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val arrayOut = PrefixAverage.recursivePrefixAverage(arrayIn)
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arrayOut `should equal` intArrayOf(
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21, 22, 23, 25, 24, 23, 22
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)
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}
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@Test
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fun testEmptyArrayRecursive() {
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val arrayIn = intArrayOf()
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val arrayOut = PrefixAverage.recursivePrefixAverage(arrayIn)
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arrayOut `should equal` intArrayOf()
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}
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@Test
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fun testOneElementArrayRecursive() {
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val arrayIn = intArrayOf(25)
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val arrayOut = PrefixAverage.recursivePrefixAverage(arrayIn)
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arrayOut `should equal` intArrayOf(25)
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}
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@Test
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fun testAlwaysSameElementArrayRecursive() {
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val arrayIn = intArrayOf(21, 21, 21, 21, 21)
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val arrayOut = PrefixAverage.recursivePrefixAverage(arrayIn)
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arrayOut `should equal` intArrayOf(21, 21, 21, 21, 21)
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}
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}
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