day 8 part 2

main.go

@@ -29,7 +29,7 @@ func main() {
 	runAndBenchmark("07", "2", false, solutions.Day07Part02)
 
 	runAndBenchmark("08", "1", false, solutions.Day08Part01)
-	runAndBenchmark("08", "2", true, solutions.Day08Part02)
+	runAndBenchmark("08", "2", false, solutions.Day08Part02)
 }
 
 type execute func(bool) int

solutions/day08.go

@@ -86,5 +86,67 @@ func Day08Part01(isTest bool) int {
 }
 
 func Day08Part02(isTest bool) int {
+	input := ReadInput("08", isTest)
+	groups := strings.Split(input, "\n")
+
+	instructionArray := make([]*InstructionStore, len(groups))
+
+	for idx, line := range groups {
+		instr, value := parseInstruction(line)
+		instructionArray[idx] = &InstructionStore{instruction: instr, value: value, executionCount: 0}
+	}
+
+	for currentExecutionCount := 0; currentExecutionCount < len(instructionArray); currentExecutionCount += 1 {
+		accumulator := 0
+		instructionPointer := 0
+		jmpNopCount := 0
+
+		for {
+			// success condition
+			if instructionPointer == len(instructionArray) {
+				return accumulator
+			}
+
+			currentInstruction := instructionArray[instructionPointer]
+			inst := currentInstruction.instruction
+			value := currentInstruction.value
+			executionCount := currentInstruction.executionCount
+
+			// If a loop is detected, break this loop
+			if executionCount == currentExecutionCount+1 {
+				break
+			}
+
+			// Check if the intruction is jmp or not, if it's the nth such instr, and change them if so)
+			if inst == nop || inst == jmp {
+				if jmpNopCount == currentExecutionCount {
+					// switch jmp & nop
+					if inst == nop {
+						inst = jmp
+					} else if inst == jmp {
+						inst = nop
+					}
+				}
+
+				jmpNopCount += 1
+			}
+
+			switch inst {
+			case nop:
+				currentInstruction.executionCount = currentExecutionCount + 1
+				instructionPointer += 1
+			case acc:
+				currentInstruction.executionCount = currentExecutionCount + 1
+				accumulator += value
+				instructionPointer += 1
+			case jmp:
+				currentInstruction.executionCount = currentExecutionCount + 1
+				instructionPointer += value
+			default:
+				panic("Found an invalid instruction while trying to execute it. " + strconv.Itoa(int(inst)))
+			}
+		}
+	}
+
 	return -1
 }