Kotlin - Change wIP

kotlin/change/README.md

@@ -0,0 +1,26 @@
+# Change
+
+Correctly determine the fewest number of coins to be given to a customer such
+that the sum of the coins' value would equal the correct amount of change.
+
+## For example
+
+- An input of 15 with [1, 5, 10, 25, 100] should return one nickel (5)
+  and one dime (10) or [0, 1, 1, 0, 0]
+- An input of 40 with [1, 5, 10, 25, 100] should return one nickel (5)
+  and one dime (10) and one quarter (25) or [0, 1, 1, 1, 0]
+
+## Edge cases
+
+- Does your algorithm work for any given set of coins?
+- Can you ask for negative change?
+- Can you ask for a change value smaller than the smallest coin value?
+
+
+
+## Source
+
+Software Craftsmanship - Kata-logue [http://craftsmanship.sv.cmu.edu/exercises/coin-change-kata](http://craftsmanship.sv.cmu.edu/exercises/coin-change-kata)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

kotlin/change/build.gradle

@@ -0,0 +1,30 @@
+buildscript {
+  ext.kotlin_version = '1.1.1'
+  repositories {
+    mavenCentral()
+  }
+  dependencies {
+    classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+  }
+}
+
+apply plugin: 'kotlin'
+
+repositories {
+  mavenCentral()
+}
+
+dependencies {
+  compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+
+  testCompile 'junit:junit:4.12'
+  testCompile "org.jetbrains.kotlin:kotlin-test-junit:$kotlin_version"
+  testCompile "org.assertj:assertj-core:2.4.1"
+
+}
+test {
+  testLogging {
+    exceptionFormat = 'full'
+    events = ["passed", "failed", "skipped"]
+  }
+}

kotlin/change/src/main/kotlin/Change.kt

@@ -0,0 +1,15 @@
+class Change(val setOfCoins: Set<Int>) {
+    fun issue(x: Int): List<Int>{
+        require((x > setOfCoins.min()!!) or (x == 0))
+        var y = x
+        val returnList = mutableListOf<Int>()
+        
+        while (y != 0){
+            val maxChange = setOfCoins.filter { y >= it }.max()
+            returnList.add(maxChange ?: 0)
+            y -= maxChange ?: 0
+        }
+
+        return returnList.reversed()
+    }
+}

kotlin/change/src/test/kotlin/ChangeTest.kt

@@ -0,0 +1,53 @@
+
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.Test
+import org.junit.Ignore
+
+class ChangeTest {
+
+
+    @Test
+    fun singleCoinChange() {
+        assertThat(Change(setOf(1, 5, 10, 25, 100)).issue(25)).containsExactly(25)
+    }
+
+    
+    @Test
+    fun multipleCoinChange() {
+        assertThat(Change(setOf(1, 5, 10, 25, 100)).issue(15)).containsExactly(5, 10)
+    }
+
+    
+    @Test
+    fun changeWithLilliputianCoins() {
+        assertThat(Change(setOf(1, 4, 15, 20, 50)).issue(23)).containsExactly(4, 4, 15)
+    }
+
+    
+    @Test
+    fun changeWithLowerElboniaCoins() {
+        assertThat(Change(setOf(1, 5, 10, 21, 25)).issue(63)).containsExactly(21,21,21)
+    }
+
+    
+    @Test
+    fun largeTargetValues() {
+        assertThat(Change(setOf(1, 2, 5, 10, 20, 50, 100)).issue(999)).containsExactly(2, 2, 5, 20, 20, 50, 100, 100, 100, 100, 100, 100, 100, 100, 100)
+    }
+
+    
+    @Test
+    fun noCoinsMake0Change() {
+        assertThat(Change(setOf(1, 5, 10, 21, 25)).issue(0)).isEmpty()
+    }
+
+    @Test(expected = IllegalArgumentException::class)
+    fun errorTestingForChangeSmallerThanTheSmallestCoin() {
+        Change(setOf(5, 10)).issue(3)
+    }
+
+    @Test(expected = IllegalArgumentException::class)
+    fun cannotFindNegativeChangeValues() {
+        Change(setOf(1, 2, 5)).issue(-5)
+    }
+}