121 lines
3.9 KiB
D
121 lines
3.9 KiB
D
import std.algorithm : countUntil, each, map;
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import std.array : array;
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import std.conv : to;
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import std.range : empty, retro;
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import std.stdio : writeln;
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import std.string : strip;
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import std.typecons : tuple;
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immutable LEFT_DIGITS = [
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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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immutable RIGHT_DIGITS = LEFT_DIGITS.map!`a.map!"a == '#' ? ' ' : '#'".array`.array;
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immutable END_SENTINEL = "# #";
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immutable MID_SENTINEL = " # # ";
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void decodeUPC(string input) {
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auto decode(string candidate) {
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int[] output;
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size_t pos = 0;
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auto next = pos + END_SENTINEL.length;
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auto part = candidate[pos .. next];
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if (part == END_SENTINEL) {
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pos = next;
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} else {
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return tuple(false, cast(int[])[]);
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}
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foreach (_; 0..6) {
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next = pos + 7;
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part = candidate[pos .. next];
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auto i = countUntil(LEFT_DIGITS, part);
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if (i >= 0) {
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output ~= i;
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pos = next;
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} else {
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return tuple(false, cast(int[])[]);
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}
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}
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next = pos + MID_SENTINEL.length;
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part = candidate[pos .. next];
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if (part == MID_SENTINEL) {
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pos = next;
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} else {
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return tuple(false, cast(int[])[]);
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}
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foreach (_; 0..6) {
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next = pos + 7;
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part = candidate[pos .. next];
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auto i = countUntil(RIGHT_DIGITS, part);
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if (i >= 0) {
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output ~= i;
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pos = next;
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} else {
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return tuple(false, cast(int[])[]);
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}
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}
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next = pos + END_SENTINEL.length;
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part = candidate[pos .. next];
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if (part == END_SENTINEL) {
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pos = next;
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} else {
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return tuple(false, cast(int[])[]);
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}
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int sum = 0;
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foreach (i,v; output) {
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if (i % 2 == 0) {
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sum += 3 * v;
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} else {
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sum += v;
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}
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}
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return tuple(sum % 10 == 0, output);
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}
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auto candidate = input.strip;
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auto output = decode(candidate);
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if (output[0]) {
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writeln(output[1]);
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} else {
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output = decode(candidate.retro.array.to!string);
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if (output[0]) {
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writeln(output[1], " Upside down");
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} else if (output[1].empty) {
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writeln("Invalid digit(s)");
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} else {
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writeln("Invalid checksum", output);
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}
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}
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}
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void main() {
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auto barcodes = [
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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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barcodes.each!decodeUPC;
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}
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