Day16: Puzzle 1 is done, pretty easy, don't know how to do part 2 yet

src/main/kotlin/com/basdado/adventofcode/day16/Day16.kt

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+package com.basdado.adventofcode.day16
+
+import com.basdado.adventofcode.line
+import java.util.stream.IntStream
+import kotlin.math.abs
+
+const val DAY16_INPUT_PATH = "/day/16/input.txt"
+
+fun main() {
+    Day16.puzzle1()
+    Day16.puzzle2()
+
+}
+
+object Day16 {
+
+    val pattern = intArrayOf(0, 1, 0, -1)
+
+    fun puzzle1() {
+        val input = line(DAY16_INPUT_PATH)
+            .chars().map { it - '0'.toInt() }
+            .toArray()
+
+        var code = input
+        IntStream.range(0, 100)
+            .peek { phase ->
+                code = IntStream.range(0, code.size).parallel()
+                    .map { output -> lastDigit(IntStream.range(0, code.size)
+                        .map { i ->  code[i] * patternAt(output, i) }
+                        .sum())}
+                    .toArray()
+            }
+//            .peek { phase -> println("Phase $phase: ${code.joinToString()} ") }
+            .skip(99)
+            .findFirst()!!
+
+        println(code.joinToString(""))
+    }
+
+    fun puzzle2() {
+        val input = line(DAY16_INPUT_PATH).repeat(10)
+            .chars().map { it - '0'.toInt() }
+            .toArray()
+
+        var code = input
+        IntStream.range(0, 100)
+            .peek { phase ->
+                code = IntStream.range(0, code.size).parallel()
+                    .map { output -> lastDigit(IntStream.range(0, code.size)
+                        .map { i ->  code[i] * patternAt(output, i) }
+                        .sum())}
+                    .toArray()
+            }
+//            .peek { phase -> println("Phase $phase: ${code.joinToString()} ") }
+            .skip(99)
+            .findFirst()!!
+
+        println(code.joinToString(""))
+    }
+
+
+    fun patternAt(output: Int, i: Int) = pattern[((i + 1) / (output + 1)) % pattern.size]
+    fun lastDigit(n: Int) = abs(n % 10)
+}

src/main/resources/day/16/ex1.txt

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+12345678

src/main/resources/day/16/input.txt

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+59727310424796235189476878806940387435291429226818921130171187957262146115559932358924341808253400617220924411865224341744614706346865536561788244183609411225788501102400269978290670307147139438239865673058478091682748114942700860895620690690625512670966265975462089087644554004423208369517716075591723905075838513598360188150158989179151879406086757964381549720210763972463291801513250953430219653258827586382953297392567981587028568433943223260723561880121205475323894070000380258122357270847092900809245133752093782889315244091880516672127950518799757198383131025701009960944008679555864631340867924665650332161673274408001712152664733237178121872