109 lines
3.7 KiB
Kotlin
109 lines
3.7 KiB
Kotlin
val LEFT_DIGITS = mapOf(
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" ## #" to 0,
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" ## #" to 1,
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" # ##" to 2,
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" #### #" to 3,
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" # ##" to 4,
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" ## #" to 5,
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" # ####" to 6,
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" ### ##" to 7,
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" ## ###" to 8,
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" # ##" to 9
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)
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val RIGHT_DIGITS = LEFT_DIGITS.mapKeys {
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it.key.replace(' ', 's').replace('#', ' ').replace('s', '#')
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}
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const val END_SENTINEL = "# #"
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const val MID_SENTINEL = " # # "
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fun decodeUPC(input: String) {
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fun decode(candidate: String): Pair<Boolean, List<Int>> {
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var pos = 0
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var part = candidate.slice(pos until pos + END_SENTINEL.length)
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if (part == END_SENTINEL) {
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pos += END_SENTINEL.length
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} else {
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return Pair(false, emptyList())
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}
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val output = mutableListOf<Int>()
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for (i in 0 until 6) {
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part = candidate.slice(pos until pos + 7)
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pos += 7
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if (LEFT_DIGITS.containsKey(part)) {
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output.add(LEFT_DIGITS.getOrDefault(part, -1))
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} else {
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return Pair(false, output.toList())
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}
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}
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part = candidate.slice(pos until pos + MID_SENTINEL.length)
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if (part == MID_SENTINEL) {
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pos += MID_SENTINEL.length
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} else {
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return Pair(false, output.toList())
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}
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for (i in 0 until 6) {
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part = candidate.slice(pos until pos + 7)
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pos += 7
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if (RIGHT_DIGITS.containsKey(part)) {
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output.add(RIGHT_DIGITS.getOrDefault(part, -1))
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} else {
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return Pair(false, output.toList())
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}
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}
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part = candidate.slice(pos until pos + END_SENTINEL.length)
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if (part == END_SENTINEL) {
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pos += END_SENTINEL.length
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} else {
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return Pair(false, output.toList())
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}
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val sum = output.mapIndexed { i, v -> if (i % 2 == 0) v * 3 else v }.sum()
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return Pair(sum % 10 == 0, output.toList())
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}
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val candidate = input.trim()
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var out = decode(candidate)
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if (out.first) {
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println(out.second)
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} else {
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out = decode(candidate.reversed())
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if (out.first) {
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print(out.second)
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println(" Upside down")
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} else {
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if (out.second.size == 12) {
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println("Invalid checksum")
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} else {
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println("Invalid digit(s)")
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}
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}
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}
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}
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fun main() {
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val barcodes = listOf(
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" # # # ## # ## # ## ### ## ### ## #### # # # ## ## # # ## ## ### # ## ## ### # # # ",
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" # # # ## ## # #### # # ## # ## # ## # # # ### # ### ## ## ### # # ### ### # # # ",
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" # # # # # ### # # # # # # # # # # ## # ## # ## # ## # # #### ### ## # # ",
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" # # ## ## ## ## # # # # ### # ## ## # # # ## ## # ### ## ## # # #### ## # # # ",
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" # # ### ## # ## ## ### ## # ## # # ## # # ### # ## ## # # ### # ## ## # # # ",
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" # # # # ## ## # # # # ## ## # # # # # #### # ## # #### #### # # ## # #### # # ",
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" # # # ## ## # # ## ## # ### ## ## # # # # # # # # ### # # ### # # # # # ",
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" # # # # ## ## # # ## ## ### # # # # # ### ## ## ### ## ### ### ## # ## ### ## # # ",
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" # # ### ## ## # # #### # ## # #### # #### # # # # # ### # # ### # # # ### # # # ",
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" # # # #### ## # #### # # ## ## ### #### # # # # ### # ### ### # # ### # # # ### # # ",
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)
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for (barcode in barcodes) {
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decodeUPC(barcode)
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}
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}
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