94 lines
2.1 KiB
C++
94 lines
2.1 KiB
C++
#include <algorithm>
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#include <cstdint>
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#include <iostream>
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#include <fstream>
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#include <iterator>
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#include <vector>
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#include <map>
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#include <tuple>
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#include <string>
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#include <numeric>
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#include <aocpp/Coord.hpp>
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#include <aocpp/Startup.hpp>
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using namespace aocpp;
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namespace {
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auto BuildLine(std::string instructions) -> std::vector<Coord>
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{
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Coord here {};
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std::vector<Coord> wire;
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auto it = std::begin(instructions);
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auto end = std::end(instructions);
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while (it != end) {
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auto start = it;
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it = std::find(it, end, ',');
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if (start == it) { throw std::runtime_error{"null command"}; }
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Coord (*step)(Coord);
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switch (*start++) {
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case 'U': step = Up; break;
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case 'D': step = Down; break;
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case 'L': step = Left; break;
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case 'R': step = Right; break;
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default: throw std::runtime_error{"bad command letter"};
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}
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auto n = std::stol(std::string{start, it});
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for (int i = 0; i < n; i++) {
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here = step(here);
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wire.push_back(here);
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}
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// skip over comma
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if (it != end) it++;
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}
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return wire;
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}
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struct Entry { bool w0, w1; std::int64_t part2; };
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auto Record (
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std::map<Coord, Entry> & m,
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bool Entry::* which,
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std::vector<Coord> const& wire
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) -> void {
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for (std::size_t i = 0; i < wire.size(); i++) {
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auto & entry = m[wire[i]];
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if (!(entry.*which)) {
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entry.*which = true;
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entry.part2 += i+1;
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}
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}
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}
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} // namespace
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auto Main(std::istream & in, std::ostream & out) -> void
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{
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std::string line;
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std::getline(in, line);
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auto wire0 = BuildLine(line);
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std::getline(in, line);
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auto wire1 = BuildLine(line);
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std::map<Coord, Entry> counts;
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Record(counts, &Entry::w0, wire0);
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Record(counts, &Entry::w1, wire1);
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std::int64_t part1 = std::numeric_limits<std::int64_t>::max();
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std::int64_t part2 = std::numeric_limits<std::int64_t>::max();
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for (auto & [k,v] : counts) {
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if (v.w0 && v.w1) {
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part1 = std::min(part1, Norm1(k));
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part2 = std::min(part2, v.part2);
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}
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}
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out << "Part 1: " << part1 << std::endl;
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out << "Part 2: " << part2 << std::endl;
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}
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