day 2

app/src/main/kotlin/day02/Day02.kt

@@ -0,0 +1,56 @@
+package day02
+
+import kotlin.math.abs
+
+class Day02 {
+    fun parse(input: String): List<List<Int>> {
+        return input.lines().map { it.split(" ").map { it.toInt() } }
+    }
+
+    fun part1(input: String): Int {
+        val parsed = parse(input)
+
+        var safeCount = 0;
+        for (line in parsed) {
+            if (isSafe(line)) {
+                safeCount += 1
+            }
+        }
+        return safeCount
+    }
+
+    fun isSafe(line: List<Int>): Boolean {
+        var neg = line[0] - line[1] < 0
+        for (i in 1..<line.count()) {
+            val diff = line[i-1] - line[i]
+            if (abs(diff) > 3 || abs(diff) < 1) {
+                return false
+            }
+            if ((diff < 0 && !neg) || (diff > 0 && neg)) {
+                return false
+            }
+        }
+        return true
+    }
+
+    fun part2(input: String): Int {
+        val parsed = parse(input)
+
+        var safeCount = 0;
+        for (line in parsed) {
+            if (isSafe(line)) {
+                safeCount += 1
+                continue
+            }
+
+            for (i in 0..<line.count()) {
+                if (isSafe(line.subList(0, i) + line.subList(i + 1, line.count()))) {
+                    safeCount += 1
+                    break
+                }
+            }
+
+        }
+        return safeCount
+    }
+}

app/src/test/kotlin/day02/Day02Test.kt

@@ -0,0 +1,42 @@
+package day02
+
+import kotlin.test.Test
+import util.InputDownloader
+
+class Day02Test {
+    val day = 2
+
+    val input = InputDownloader().getInput(day)
+    val example = InputDownloader().getExample(day)
+
+    @Test fun part1Example() {
+        part1(example, 2)
+    }
+
+    @Test fun part2Example() {
+        part2(example, 4)
+    }
+
+    @Test fun part1Solution() {
+        part1(input, 663)
+    }
+
+    @Test fun part2Solution() {
+        part2(input, 692)
+    }
+
+
+    fun part1(input: String, expected: Int) {
+        val day = Day02()
+        val output = day.part1(input)
+        println("output: $output")
+        assert(output == expected)
+    }
+
+    fun part2(input: String, expected: Int) {
+        val day = Day02()
+        val output = day.part2(input)
+        println("output: $output")
+        assert(output == expected)
+    }
+}