Solution 2015-05 (Doesn't He Have Intern-Elves For This?)

Author: rhaendel

src/main/kotlin/de/ronny_h/aoc/year2015/day05/InternElves.kt

@@ -0,0 +1,51 @@
+package de.ronny_h.aoc.year2015.day05
+
+import de.ronny_h.aoc.AdventOfCode
+
+fun main() = InternElves().run(255, 55)
+
+class InternElves : AdventOfCode<Int>(2015, 5) {
+    override fun part1(input: List<String>): Int = input
+        .filter(::hasThreeVowels)
+        .filter(::hasALetterTwiceInARow)
+        .count(::doesNotContainBadStrings)
+
+    private val vowels = setOf('a', 'e', 'i', 'o', 'u')
+    private val badStrings = setOf("ab", "cd", "pq", "xy")
+
+    fun hasThreeVowels(string: String) = string.filter { it in vowels }.length >= 3
+
+    fun hasALetterTwiceInARow(string: String): Boolean {
+        for (i in string.indices) {
+            if (i != string.lastIndex && string[i] == string[i + 1]) return true
+        }
+        return false
+    }
+
+    fun doesNotContainBadStrings(string: String) = badStrings.all { !string.contains(it) }
+
+    override fun part2(input: List<String>): Int = input
+        .filter(::containsAPairOfLettersAtLeastTwiceWithoutOverlapping)
+        .count(::containsALetterRepeatingWithExactlyOneLetterInBetween)
+
+    fun containsAPairOfLettersAtLeastTwiceWithoutOverlapping(string: String): Boolean {
+        for (i in string.indices) {
+            if (i < string.lastIndex - 1) {
+                val pair = "${string[i]}${string[i + 1]}"
+                if (string.findAnyOf(listOf(pair), i + 2) != null) {
+                    return true
+                }
+            }
+        }
+        return false
+    }
+
+    fun containsALetterRepeatingWithExactlyOneLetterInBetween(string: String): Boolean {
+        for (i in string.indices) {
+            if (i < string.lastIndex - 1) {
+                if (string[i] == string[i + 2]) return true
+            }
+        }
+        return false
+    }
+}

src/test/kotlin/de/ronny_h/aoc/year2015/day05/InternElvesTest.kt

@@ -0,0 +1,48 @@
+package de.ronny_h.aoc.year2015.day05
+
+import io.kotest.core.spec.style.StringSpec
+import io.kotest.matchers.shouldBe
+
+class InternElvesTest : StringSpec({
+
+    val internElves = InternElves()
+
+    "part 1: A nice string contains at least three vowels" {
+        internElves.hasThreeVowels("aei") shouldBe true
+        internElves.hasThreeVowels("ugknbfddgicrmopn") shouldBe true
+    }
+
+    "part 1: A nice string contains at least one letter that appears twice in a row" {
+        internElves.hasALetterTwiceInARow("ugknbfddgicrmopn") shouldBe true
+    }
+
+    "part 1: A nice string does not contain the strings ab, cd, pq, or xy" {
+        internElves.doesNotContainBadStrings("ugknbfddgicrmopn") shouldBe true
+    }
+
+    "part 1: The number of nice strings" {
+        internElves.part1(listOf("ugknbfddgicrmopn")) shouldBe 1
+        internElves.part1(listOf("aaa")) shouldBe 1
+        internElves.part1(listOf("jchzalrnumimnmhp", "haegwjzuvuyypxyu", "dvszwmarrgswjxmb")) shouldBe 0
+    }
+
+    "part 2: A nice string contains a pair of any two letters that appears at least twice in the string without overlapping" {
+        internElves.containsAPairOfLettersAtLeastTwiceWithoutOverlapping("xyxy") shouldBe true
+        internElves.containsAPairOfLettersAtLeastTwiceWithoutOverlapping("aabcdefgaa") shouldBe true
+        internElves.containsAPairOfLettersAtLeastTwiceWithoutOverlapping("aaa") shouldBe false
+    }
+
+    "part 2: A nice string contains at least one letter which repeats with exactly one letter between them" {
+        internElves.containsALetterRepeatingWithExactlyOneLetterInBetween("xyx") shouldBe true
+        internElves.containsALetterRepeatingWithExactlyOneLetterInBetween("abcdefeghi") shouldBe true
+        internElves.containsALetterRepeatingWithExactlyOneLetterInBetween("abcdefeghi") shouldBe true
+        internElves.containsALetterRepeatingWithExactlyOneLetterInBetween("aaa") shouldBe true
+        internElves.containsALetterRepeatingWithExactlyOneLetterInBetween("abc") shouldBe false
+    }
+
+    "part 2: The number of nice strings" {
+        internElves.part2(listOf("qjhvhtzxzqqjkmpb")) shouldBe 1
+        internElves.part2(listOf("xxyxx")) shouldBe 1
+        internElves.part2(listOf("uurcxstgmygtbstg", "uurcxstgmygtbstg")) shouldBe 0
+    }
+})