73 lines
2.0 KiB
D
73 lines
2.0 KiB
D
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module day12.part1;
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import std.file;
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import std.stdio;
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import std.string;
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import std.algorithm;
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import std.conv;
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import std.array;
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bool isLarge(string name) {
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return name.toUpper() == name;
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}
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void registerPath(ref string[][string] paths, string[] caves) {
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if (caves[0] !in paths) {
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paths[caves[0]] = [caves[1]];
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} else {
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paths[caves[0]] ~= caves[1];
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}
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if (caves[1] !in paths) {
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paths[caves[1]] = [caves[0]];
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} else {
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paths[caves[1]] ~= caves[0];
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}
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}
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uint[string] getVisitCounts(string[] history) {
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uint[string] visitCounts;
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foreach (p; history) {
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if (p !in visitCounts) {
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visitCounts[p] = 1;
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} else {
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visitCounts[p]++;
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}
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}
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return visitCounts;
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}
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bool canVisit(string cave, string[] history) {
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if (cave.isLarge) return true;
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uint[string] visitCounts = getVisitCounts(history);
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bool visitedSmallCaveTwice = false;
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foreach (p, c; visitCounts) {
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if (!p.isLarge && c > 1) {
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visitedSmallCaveTwice = true;
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break;
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}
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}
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uint availablePathVisitCount = visitCounts.require(cave, 0);
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return visitedSmallCaveTwice ? availablePathVisitCount < 1 : availablePathVisitCount < 2;
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}
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string[][] findPaths(ref string[][string] paths, string cave, string[] history) {
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if (cave == "end") return [history ~ cave];
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string[][] nextPaths = [];
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foreach (availablePath; paths[cave]) {
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if (availablePath == "start") continue;
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if (canVisit(availablePath, history ~ cave)) nextPaths ~= findPaths(paths, availablePath, history ~ cave);
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}
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return nextPaths;
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}
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void passagePathing() {
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string[] pathDescriptors = readText("source/day12/input.txt").strip.split("\n")
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.map!(s => s.strip).array;
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string[][string] paths;
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foreach (desc; pathDescriptors) {
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registerPath(paths, desc.split("-"));
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}
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findPaths(paths, "start", [])
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.map!(p => p.joiner!(string[], string)(",").to!string)
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.array.length.writeln;
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}
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