import Foundation

typealias Op = (Bool, Bool) -> Bool
typealias Gate  = (String, Op, String, String)

struct Circuit : CustomStringConvertible {
    let gates: [Gate]
    var nodes: [String: Bool]
    var pendingEndNodes: Set<String>
    var description: String {
        nodes.map { "\($0): \($1 ? 1 : 0)" }.sorted().joined(separator: "\n") +
        "\n\(pendingEndNodes)"
    }
    var value: Int? {
        if pendingEndNodes.count > 0 { return nil }
        return nodes.keys.filter { $0.starts(with: "z") }
            .sorted().reversed().reduce(0) { $0*2 + (nodes[$1]! ? 1 : 0) }
    }
    mutating func run(gate: Gate) {
        let (in1, op, in2, out) = gate
        if let v1 = nodes[in1], let v2 = nodes[in2] {
            nodes[out] = op(v1, v2)
            pendingEndNodes.remove(out)
        }
    }
    mutating func run() {
        gates.forEach { run(gate: $0) }
    }
}

func readInput(_ filePath: String) throws -> Circuit {
    let content = try String(contentsOfFile: filePath, encoding: .ascii)
    let nodeRe = try Regex(#"([a-z0-9]+): (0|1)"#)
    let gateRe = try Regex(#"([a-z0-9]+) (AND|OR|XOR) ([a-z0-9]+) -> ([a-z0-9]+)"#)
    let opMap: [String: Op] = [
        "AND": { $0 && $1 },
        "OR": { $0 || $1 },
        "XOR": { $0 != $1 }
    ]
    var nodes: [String: Bool] = [:]
    var gates: [Gate] = []
    var endNodes: Set<String> = []
    for line in content.split(separator: "\n") {
        if let m = line.wholeMatch(of: nodeRe) {
            let node = String(m.output[1].substring!)
            let val = m.output[2].substring! == "1"
            nodes[node] = val
        }
        if let m = line.wholeMatch(of: gateRe) {
            let in1 = String(m.output[1].substring!)
            let op = opMap[String(m.output[2].substring!)]!
            let in2 = String(m.output[3].substring!)
            let out = String(m.output[4].substring!)
            gates.append((in1, op, in2, out))
            if out.starts(with: "z") {
                endNodes.insert(out)
            }
        }
    }
    return Circuit(gates: gates, nodes: nodes, pendingEndNodes: endNodes)
} 

var circuit = try readInput(CommandLine.arguments[1])
//print(circuit)
while true {
    if let res = circuit.value {
        print("answer: \(res)")
        break
    }
    circuit.run()
    //print(circuit)
}