From 2232caefd9eda0fc1bf72be4a75d93c0c5b6a502 Mon Sep 17 00:00:00 2001
From: Sander in 't Hout <sander@inthout.me>
Date: Wed, 18 Dec 2024 17:36:12 +0100
Subject: [PATCH] Add AoC 2024 day 17 part 1 solver

---
 assets/advent_of_code/2024_17_sample.txt      |  5 +
 .../advent_of_code/2024/_all_solvers.dart     |  1 +
 .../advent_of_code/2024/day_17_solver.dart    | 93 +++++++++++++++++++
 3 files changed, 99 insertions(+)
 create mode 100644 assets/advent_of_code/2024_17_sample.txt
 create mode 100644 lib/solvers/advent_of_code/2024/day_17_solver.dart

diff --git a/assets/advent_of_code/2024_17_sample.txt b/assets/advent_of_code/2024_17_sample.txt
new file mode 100644
index 0000000..36fbf8d
--- /dev/null
+++ b/assets/advent_of_code/2024_17_sample.txt
@@ -0,0 +1,5 @@
+Register A: 729
+Register B: 0
+Register C: 0
+
+Program: 0,1,5,4,3,0
\ No newline at end of file
diff --git a/lib/solvers/advent_of_code/2024/_all_solvers.dart b/lib/solvers/advent_of_code/2024/_all_solvers.dart
index 5a6b3d9..1bdb038 100644
--- a/lib/solvers/advent_of_code/2024/_all_solvers.dart
+++ b/lib/solvers/advent_of_code/2024/_all_solvers.dart
@@ -12,3 +12,4 @@ export 'day_12_solver.dart';
 export 'day_13_solver.dart';
 export 'day_14_solver.dart';
 export 'day_15_solver.dart';
+export 'day_17_solver.dart';
diff --git a/lib/solvers/advent_of_code/2024/day_17_solver.dart b/lib/solvers/advent_of_code/2024/day_17_solver.dart
new file mode 100644
index 0000000..fa0338d
--- /dev/null
+++ b/lib/solvers/advent_of_code/2024/day_17_solver.dart
@@ -0,0 +1,93 @@
+import 'package:h3x_devtools/solvers/advent_of_code/2024/aoc_2024_solver.dart';
+
+class Day17Solver extends AdventOfCode2024Solver {
+
+  @override
+  final int dayNumber = 17;
+
+  @override
+  String getSolution(String input) {
+    String splitNewline = input.contains('\r\n\r\n') ? '\r\n\r\n' : input.contains('\r\r') ? '\r\r' : '\n\n';
+    List<String> inputParts = input.split(splitNewline);
+
+    List<String> registers = inputParts[0].splitLines().toList();
+    int registerA = int.parse(registers[0].split('Register A: ')[1]);
+    int registerB = int.parse(registers[1].split('Register B: ')[1]);
+    int registerC = int.parse(registers[2].split('Register C: ')[1]);
+
+    List<int> instructions = inputParts[1].split('Program: ')[1].split(',').toIntList();
+
+    // Part 1
+    List<int> output = _runProgram(instructions, registerA, registerB, registerC);
+
+    return 'Program output: ${output.join(',')}';
+  }
+
+  int test(int getal, List<int> instructions, int initialRegisterA, int initialRegisterB, int initialRegisterC) {
+    List<int> x =  _runProgram(instructions, initialRegisterA, initialRegisterB, initialRegisterC);
+    if (x.length < instructions.length) {
+      return -1;
+    } else if (x.length > instructions.length) {
+      return 1;
+    } else {
+      for (int i = 0; i < instructions.length; i++) {
+        if (x[i] < instructions[i]) return -1;
+        if (x[i] > instructions[i]) return 1;
+      }
+    }
+
+    return 0;
+  }
+
+  List<int> _runProgram(List<int> instructions, int initialRegisterA, int initialRegisterB, int initialRegisterC) {
+    int registerA = initialRegisterA, registerB = initialRegisterB, registerC = initialRegisterC;
+    int instructionPointer = 0;
+    List<int> output = [];
+
+    while (instructionPointer <= instructions.length - 2) {
+      int operand = instructions[instructionPointer + 1];
+      int comboOperand = _getComboOperandValue(registerA, registerB, registerC, operand);
+      bool updateInstructionPointer = true;
+
+      switch (instructions[instructionPointer]) {
+        case 0: // adv
+          registerA ~/= pow(2, comboOperand);
+        case 1: // bxl
+          registerB ^= operand;
+        case 2: // bst
+          registerB = comboOperand % 8;
+        case 3: // jnz
+          if (registerA != 0) {
+            instructionPointer = operand;
+            updateInstructionPointer = false;
+          }
+        case 4: // bxc
+          registerB ^= registerC;
+        case 5: // out
+          output.add(comboOperand % 8);
+        case 6: // bdv
+          registerB = registerA ~/ pow(2, comboOperand);
+        case 7: // cdv
+          registerC = registerA ~/ pow(2, comboOperand);
+        default:
+          throw Exception('Could not parse instruction');
+      }
+
+      if (updateInstructionPointer) instructionPointer += 2;
+    }
+
+    return output;
+  }
+
+  int _getComboOperandValue(int registerA, int registerB, int registerC, int operand) {
+    return switch (operand) {
+      >= 0 && <= 3 => operand,
+      4 => registerA,
+      5 => registerB,
+      6 => registerC,
+      7 => throw Exception('Reserved, should not be seen in valid programs'),
+      _ => throw Exception('Invalid'),
+    };
+  }
+
+}