bpavuk.neocities.org
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src/07/solution.cxx
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src/07/solution.cxx
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#include <format>
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#include <fstream>
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#include <map>
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#include <optional>
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#include <print>
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#include <string>
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#include <vector>
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};
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long long count_possible_paths(std::vector<std::string> &data,
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Position position, long long acc,
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Position position,
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std::map<std::string, long long> &cache) {
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// TODO
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std::optional<Position> new_pos{};
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long long new_acc = acc;
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if (position.y == data.size()) { // if we reached bottom
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return acc + 1;
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return 1;
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}
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long long result = 0;
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if (data[position.y][position.x] == '|' ||
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data[position.y][position.x] == 'S') {
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new_pos = Position{.x = position.x, .y = position.y + 1};
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Position new_pos{.x = position.x, .y = position.y + 1};
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result = count_possible_paths(data, new_pos, cache);
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} else if (data[position.y][position.x] == '^') {
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Position left = Position{.x = position.x - 1, .y = position.y};
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Position right = Position{.x = position.x + 1, .y = position.y};
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// a weird workaround to satisfy some static checks. maps must be sortable.
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if (cache.contains(position.encode())) {
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new_acc = cache[position.encode()];
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result = cache[position.encode()];
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} else {
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new_acc = count_possible_paths(data, left, 0, cache) +
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count_possible_paths(data, right, 0, cache);
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result = count_possible_paths(data, left, cache) +
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count_possible_paths(data, right, cache);
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cache[position.encode()] = new_acc;
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cache[position.encode()] = result;
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}
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}
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if (!new_pos.has_value()) {
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return new_acc;
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}
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__attribute__((musttail)) return count_possible_paths(data, new_pos.value(),
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new_acc, cache);
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return result;
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}
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long long count_possible_paths(std::vector<std::string> &data,
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.x = data[0].find_first_of('S'),
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.y = 0,
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};
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return count_possible_paths(data, start, 1, cache);
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return count_possible_paths(data, start, cache);
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}
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// runtime on Ryzen 5 5600G: 0.018s
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// runtime on Ryzen 5 5600G: 0.004s
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int main() {
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auto data_path = get_input_path(DATA_FOLDER);
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std::ifstream data_ifstream(data_path);