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fiddle with 2022-12

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This commit is contained in:
Eric Mertens 2023-03-22 14:02:29 -07:00
parent de648bc578
commit de2117327e
1 changed files with 20 additions and 27 deletions
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47
2022/12.cpp
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@ -1,5 +1,6 @@
#include <cstdint> #include <cstdint>
#include <iostream> #include <iostream>
#include <optional>
#include <set> #include <set>
#include <sstream> #include <sstream>
#include <tuple> #include <tuple>
@ -16,55 +17,47 @@ using aocpp::Grid;
namespace { namespace {
auto Parse(std::istream & in) -> std::tuple<Coord, Coord, Grid> auto Parse(std::istream & in) -> std::tuple<Coord, std::vector<Coord>, Coord, Grid>
{ {
Coord start {}; Coord start1 {};
std::vector<Coord> starts2;
Coord end {}; Coord end {};
auto grid = Grid::Parse(in); auto grid = Grid::Parse(in);
grid.each([&](Coord c, char v) { grid.each([&](Coord c, char v) {
switch (v) { switch (v) {
case 'S': grid[c] = 'a'; start = c; break; case 'S': grid[c] = 'a'; start1 = c; break;
case 'E': grid[c] = 'z'; end = c; break; case 'E': grid[c] = 'z'; end = c; break;
case 'a': starts2.push_back(c); break;
} }
}); });
return {start, end, std::move(grid)}; return {start1, std::move(starts2), end, std::move(grid)};
} }
auto Solve(std::vector<Coord> starts, Coord end, Grid const& grid) -> std::int64_t auto Solve(std::vector<Coord> starts, Coord end, Grid const& grid) -> std::optional<std::int64_t>
{ {
std::vector<Coord> prev_layer(std::move(starts));
std::vector<Coord> next_layer; std::vector<Coord> next_layer;
std::set<Coord> seen; std::set<Coord> seen;
std::int64_t counter {1}; std::int64_t counter {1};
while (!prev_layer.empty()) { while (!starts.empty()) {
for (auto here : prev_layer) { for (auto here : starts) {
if (!seen.insert(here).second) continue; if (!seen.insert(here).second) continue;
auto here_height = grid[here]; auto here_height = grid[here];
for (auto next : {Up(here), Down(here), Left(here), Right(here)}) { for (auto next : {Up(here), Down(here), Left(here), Right(here)}) {
if (!grid.contains(next)) continue; if (!grid.contains(next)) continue;
if (grid[next] - here_height > 1) continue; if (grid[next] - 1 > here_height) continue;
if (next == end) { return counter; } if (next == end) { return counter; }
next_layer.push_back(next); next_layer.push_back(next);
} }
} }
counter++; counter++;
prev_layer.clear(); starts.clear();
std::swap(prev_layer, next_layer); std::swap(starts, next_layer);
} }
return -1; return {};
}
auto Part2Starts(Grid const& grid) -> std::vector<Coord>
{
std::vector<Coord> starts;
grid.each([&](Coord c, char v) {
if (v == 'a') starts.push_back(c);
});
return starts;
} }
} // namespace } // namespace
@ -78,15 +71,15 @@ TEST_SUITE("2022-12 examples") {
"acctuvwj\n" "acctuvwj\n"
"abdefghi\n" "abdefghi\n"
}; };
auto [start, end, grid] = Parse(in); auto [start1, starts2, end, grid] = Parse(in);
CHECK(31 == Solve({start}, end, grid)); CHECK(31 == Solve({start1}, end, grid));
CHECK(29 == Solve(Part2Starts(grid), end, grid)); CHECK(29 == Solve(std::move(starts2), end, grid));
} }
} }
auto Main(std::istream & in, std::ostream & out) -> void auto Main(std::istream & in, std::ostream & out) -> void
{ {
auto const [start, end, grid] = Parse(in); auto [start1, starts2, end, grid] = Parse(in);
out << "Part 1: " << Solve({start}, end, grid) << std::endl; out << "Part 1: " << Solve({start1}, end, grid).value_or(-1) << std::endl;
out << "Part 2: " << Solve(Part2Starts(grid), end, grid) << std::endl; out << "Part 2: " << Solve(std::move(starts2), end, grid).value_or(-1) << std::endl;
} }