93 lines
2.1 KiB
C++
93 lines
2.1 KiB
C++
#include <cstdint>
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#include <iostream>
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#include <set>
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#include <sstream>
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#include <tuple>
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#include <vector>
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#include <doctest.h>
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#include <aocpp/Coord.hpp>
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#include <aocpp/Grid.hpp>
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#include <aocpp/Startup.hpp>
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using aocpp::Coord;
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using aocpp::Grid;
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namespace {
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auto Parse(std::istream & in) -> std::tuple<Coord, Coord, Grid>
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{
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Coord start {};
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Coord end {};
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auto grid = Grid::Parse(in);
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grid.each([&](Coord c, char v) {
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switch (v) {
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case 'S': grid[c] = 'a'; start = c; break;
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case 'E': grid[c] = 'z'; end = c; break;
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}
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});
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return {start, end, std::move(grid)};
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}
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auto Solve(std::vector<Coord> starts, Coord end, Grid const& grid) -> std::int64_t
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{
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std::vector<Coord> prev_layer(std::move(starts));
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std::vector<Coord> next_layer;
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std::set<Coord> seen;
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std::int64_t counter {1};
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while (!prev_layer.empty()) {
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for (auto here : prev_layer) {
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if (!seen.insert(here).second) continue;
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auto here_height = grid[here];
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for (auto next : {Up(here), Down(here), Left(here), Right(here)}) {
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if (!grid.contains(next)) continue;
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if (grid[next] - here_height > 1) continue;
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if (next == end) { return counter; }
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next_layer.push_back(next);
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}
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}
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counter++;
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prev_layer.clear();
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std::swap(prev_layer, next_layer);
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}
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return -1;
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}
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auto Part2Starts(Grid const& grid) -> std::vector<Coord>
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{
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std::vector<Coord> starts;
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grid.each([&](Coord c, char v) {
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if (v == 'a') starts.push_back(c);
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});
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return starts;
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}
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} // namespace
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TEST_SUITE("2022-12 examples") {
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TEST_CASE("documented example") {
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std::istringstream in {
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"Sabqponm\n"
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"abcryxxl\n"
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"accszExk\n"
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"acctuvwj\n"
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"abdefghi\n"
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};
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auto [start, end, grid] = Parse(in);
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CHECK(31 == Solve({start}, end, grid));
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CHECK(29 == Solve(Part2Starts(grid), end, grid));
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}
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}
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auto main(int argc, char** argv) -> int
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{
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auto [start, end, grid] = Parse(*aocpp::Startup(argc, argv));
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std::cout << "Part 1: " << Solve({start}, end, grid) << std::endl;
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std::cout << "Part 2: " << Solve(Part2Starts(grid), end, grid) << std::endl;
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}
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