75 lines
2.2 KiB
C++
75 lines
2.2 KiB
C++
//
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// Created by mgretton on 09/12/2021.
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//
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#include <iostream>
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#include <set>
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#include <string>
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#include <vector>
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using Depths = std::vector<std::string>;
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using Coord = std::pair<std::size_t, std::size_t>;
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using Coords = std::set<Coord>;
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auto find_basin_size(std::size_t x1, std::size_t y1, Depths const& depths) -> std::size_t
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{
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Coords visited;
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Coords to_visit;
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to_visit.insert({x1, y1});
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while (!to_visit.empty()) {
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Coords next_to_visit;
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for (auto const& coord : to_visit) {
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auto x{coord.first};
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auto y{coord.second};
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if (x > 0 && depths[y][x - 1] != '9' && !visited.contains({x - 1, y})) {
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next_to_visit.insert({x - 1, y});
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visited.insert({x - 1, y});
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}
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if (y > 0 && depths[y - 1][x] != '9' && !visited.contains({x, y - 1})) {
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next_to_visit.insert({x, y - 1});
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visited.insert({x, y - 1});
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}
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if (x < depths[y].size() - 1 && depths[y][x + 1] != '9' && !visited.contains({x + 1, y})) {
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next_to_visit.insert({x + 1, y});
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visited.insert({x + 1, y});
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}
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if (y < depths.size() - 1 && depths[y + 1][x] != '9' && !visited.contains({x, y + 1})) {
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next_to_visit.insert({x, y + 1});
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visited.insert({x, y + 1});
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}
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}
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std::swap(next_to_visit, to_visit);
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}
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return visited.size();
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}
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auto main() -> int
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{
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Depths depths;
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std::string line;
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while (std::getline(std::cin, line)) {
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depths.push_back(line);
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}
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std::vector<std::size_t> basin_sizes;
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for (std::size_t y{0}; y < depths.size(); ++y) {
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for (std::size_t x{0}; x < depths[y].size(); ++x) {
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bool min = true;
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min &= (x == 0) || (depths[y][x - 1] > depths[y][x]);
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min &= (y == 0) || (depths[y - 1][x] > depths[y][x]);
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min &= (x == depths[y].size() - 1) || (depths[y][x + 1] > depths[y][x]);
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min &= (y == depths.size() - 1) || (depths[y + 1][x] > depths[y][x]);
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if (min) {
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basin_sizes.push_back(find_basin_size(x, y, depths));
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}
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}
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}
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std::sort(basin_sizes.begin(), basin_sizes.end());
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std::reverse(basin_sizes.begin(), basin_sizes.end());
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std::cout << "Result " << basin_sizes[0] << " * " << basin_sizes[1] << " * " << basin_sizes[2]
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<< " = " << basin_sizes[0] * basin_sizes[1] * basin_sizes[2] << '\n';
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return 0;
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}
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