Day02.swift

import Foundation
import Tools

final class Day02Solver: DaySolver {
	let dayNumber: Int = 2

	struct Input {
		let program: [Int]
	}

	//    private enum Instruction {
	//        case add(operandIndex1: Int, operandIndex2: Int, targetIndex: Int)
	//        case mul(operandIndex1: Int, operandIndex2: Int, targetIndex: Int)
	//        case halt
	//    }
//
	//    private func executeProgram(_ originalOrogram: [Int]) -> Int {
	//        var program = originalOrogram
//
	//        var ip = 0
//
	//        instructionLoop: while ip < program.count {
	//            let instruction: Instruction
//
	//            switch program[ip] {
	//            case 1:
	//                instruction = .add(operandIndex1: program[ip + 1], operandIndex2: program[ip + 2], targetIndex: program[ip + 3])
	//            case 2:
	//                instruction = .mul(operandIndex1: program[ip + 1], operandIndex2: program[ip + 2], targetIndex: program[ip + 3])
	//            case 99:
	//                instruction = .halt
	//            default: fatalError("Unknown instruction")
	//            }
//
	//            switch instruction {
	//            case .add(let operandIndex1, let operandIndex2, let targetIndex):
	//                program[targetIndex] = program[operandIndex1] + program[operandIndex2]
	//            case .mul(let operandIndex1, let operandIndex2, let targetIndex):
	//                program[targetIndex] = program[operandIndex1] * program[operandIndex2]
	//            case .halt:
	//                break instructionLoop
	//            }
//
	//            ip += 4
	//        }
//
	//        return program[0]
	//    }

	func solvePart1(withInput input: Input) -> Int {
		var program = input.program

		program[1] = 12
		program[2] = 2

		let intcode = IntcodeProcessor()

		return intcode.executeProgram(program, input: []).memory[0]
	}

	func solvePart2(withInput input: Input) -> Int {
		let intcode = IntcodeProcessor()

		var program = input.program

		for noun in 0 ... 99 {
			for verb in 0 ... 99 {
				program[1] = noun
				program[2] = verb

				if intcode.executeProgram(program, input: []).memory[0] == 19690720 {
					return 100 * noun + verb
				}
			}
		}

		return -1
	}

	func parseInput(rawString: String) -> Input {
		return .init(program: rawString.parseCommaSeparatedInts())
	}
}