day17

Author: spaenleh

Sources/AdventOfCode.swift

@@ -2,22 +2,22 @@ import ArgumentParser
 
 // Add each new day implementation to this array:
 let allChallenges: [any AdventDay] = [
-  Day01(),
-  Day02(),
-  Day03(),
-  Day04(),
-  Day05(),
-  Day06(),
-  Day07(),
-  Day08(),
-  Day09(),
-  Day10(),
-  Day11(),
-  Day12(),
-  Day13(),
-  Day14(),
-  Day15(),
-  Day17(),
+  // Day01(),
+  // Day02(),
+  // Day03(),
+  // Day04(),
+  // Day05(),
+  // Day06(),
+  // Day07(),
+  // Day08(),
+  // Day09(),
+  // Day10(),
+  // Day11(),
+  // Day12(),
+  // Day13(),
+  // Day14(),
+  // Day15(),
+  Day17()
 ]
 
 @main

Sources/Day17.swift

@@ -23,67 +23,47 @@ struct Computer {
   }
 
   mutating func executeOp(_ ops: Int, _ operand: Int, combo comboOp: Int, pointer: Int) -> Int {
-    var p = pointer
     func div(_ num: Int, _ denomShift: Int) -> Int {
       let denom = 1 << denomShift
       if denom > num || denomShift > num {
         return 0
       }
-      if denom == 0 {
-        print("division by zero")
-        print("denomShift", denomShift)
-      }
       return num / denom
     }
 
     switch ops {
     case 0:
       // adv
-      let res = div(comboOp, registers.A)
-      print("adv", res)
-      registers.A = res
-      p += 2
+      registers.A = div(registers.A, comboOp)
     case 1:
       // bxl
       let res = registers.B ^ operand
-      print("bxl", res)
       registers.B = res
-      p += 2
     case 2:
       //bst
       let res = comboOp % 8
-      print("bst", operand, res)
       registers.B = res
-      p += 2
     case 3:
       // jnz
       if registers.A != 0 {
-        // jump by the value of the operand
-        p += comboOp
-      } else {
-        // simple increase
-        p += 2
+        // set the pointer to the value of the operand
+        return operand
       }
     case 4:
       // bxc
       registers.B ^= registers.C
-      // do nothing with operand
-      p += 2
     case 5:
       // out
       output.append(comboOp % 8)
-      p += 2
     case 6:
       // bdv
-      registers.B = div(comboOp, registers.A)
-      p += 2
+      registers.B = div(registers.A, comboOp)
     case 7:
       // cdv
-      registers.C = div(comboOp, registers.A)
-      p += 2
+      registers.C = div(registers.A, comboOp)
     default: break
     }
-    return p
+    return pointer + 2
   }
 
   mutating func execute() -> String {
@@ -104,7 +84,7 @@ struct Day17: AdventDay {
   var data: String
 
   func initialize() -> (instructions: [Int], registers: Registers) {
-    let parts = data.split(separator: "\n\n")
+    let parts = data.trimmed().split(separator: "\n\n")
     let instructions = parts[1].trimmingPrefix("Program: ").integers(separator: ",")
     var registers = Registers()
     if let match = parts[0].firstMatch(
@@ -120,6 +100,7 @@ struct Day17: AdventDay {
   func part1() -> String {
     let (instructions, registers) = initialize()
     var computer = Computer(instructions: instructions, registers: registers)
+
     return computer.execute()
   }