Day 2

src/main/kotlin/com/basdado/adventofcode/Utils.kt

@@ -8,4 +8,8 @@ fun lines(resourceFile: String): Stream<String> {
     return Files.lines(Paths.get(Utils::class.java.getResource(resourceFile).toURI()))
 }
 
+fun line(resourceFile: String): String {
+    return lines(resourceFile).findFirst().get()
+}
+
 class Utils

src/main/kotlin/com/basdado/adventofcode/day2/Day2.kt

@@ -0,0 +1,75 @@
+package com.basdado.adventofcode.day2
+
+import com.basdado.adventofcode.line
+import com.basdado.adventofcode.lines
+import java.lang.Exception
+
+const val DAY2_INPUT_PATH = "/day/2/input.txt"
+
+fun main() {
+    Day2.puzzle1()
+    Day2.puzzle2()
+}
+
+object Day2 {
+
+    val opcodes = mapOf(
+        Pair(1, ::add),
+        Pair(2, ::multiply)
+    )
+
+    private fun add(program: IntArray, pos1: Int, pos2: Int, pos3: Int) {
+        program[pos3] = program[pos1] + program[pos2]
+    }
+
+    private fun multiply(program: IntArray, pos1: Int, pos2: Int, pos3: Int) {
+        program[pos3] = program[pos1] * program[pos2]
+    }
+
+    fun puzzle1() {
+        val input = parseInput(line(DAY2_INPUT_PATH))
+//        val input = parseInput("1,9,10,3,2,3,11,0,99,30,40,50")
+        input[1] = 12
+        input[2] = 2
+//        println(input.joinToString())
+        execute(input)
+//        println(input.joinToString())
+        println(input[0])
+    }
+
+    fun puzzle2() {
+        val input = parseInput(line(DAY2_INPUT_PATH))
+
+        for (noun in 0..100) {
+            for (verb in 0..100) {
+                val program = input.copyOf()
+                program[1] = noun
+                program[2] = verb
+                try {
+                    execute(program)
+                } catch (e: Exception) {
+                    // Program is buggy with these inputs...whatever
+                }
+                if (program[0] == 19690720) {
+                    // Success!
+                    println("noun: $noun, verb: $verb, result: ${100 * noun + verb}")
+                }
+            }
+        }
+    }
+
+    fun parseInput(input: String): IntArray {
+        return input.split(",").map { it.toInt() }.toIntArray();
+    }
+
+    fun execute(program: IntArray) {
+        var pos = 0
+        while(program[pos] != 99) {
+
+            val op = opcodes[program[pos]] ?: error("Unknown opcode at position $pos")
+            op(program, program[pos+1], program[pos+2], program[pos+3])
+            pos += 4
+        }
+
+    }
+}

src/main/resources/day/2/input.txt

@@ -0,0 +1 @@
+1,0,0,3,1,1,2,3,1,3,4,3,1,5,0,3,2,1,10,19,1,6,19,23,2,23,6,27,2,6,27,31,2,13,31,35,1,10,35,39,2,39,13,43,1,43,13,47,1,6,47,51,1,10,51,55,2,55,6,59,1,5,59,63,2,9,63,67,1,6,67,71,2,9,71,75,1,6,75,79,2,79,13,83,1,83,10,87,1,13,87,91,1,91,10,95,2,9,95,99,1,5,99,103,2,10,103,107,1,107,2,111,1,111,5,0,99,2,14,0,0