65 lines
1.5 KiB
C++
65 lines
1.5 KiB
C++
#include <cassert>
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#include <iostream>
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#include <map>
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#include <string>
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struct InTree
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{
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constexpr auto visited() const noexcept -> bool { return visited_; }
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constexpr void visit() { visited_ = true; }
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private:
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bool visited_{false};
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};
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using UInt = unsigned long;
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using VisitMap = std::map<UInt, InTree>;
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using Connections = std::multimap<UInt, UInt>;
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auto find_next_node(VisitMap& map)
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{
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return std::find_if(map.begin(), map.end(), [](auto const& it) { return !it.second.visited(); });
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}
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auto main() -> int
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{
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std::string line;
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Connections connections;
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while (std::getline(std::cin, line) && !line.empty()) {
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std::size_t end{0};
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auto from{std::stoul(line, &end)};
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assert(line.substr(end, 5) == " <-> ");
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auto idx{end + 5};
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while (idx < line.size()) {
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if (line[idx] == ',' || line[idx] == ' ') {
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++idx;
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continue;
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}
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auto to{std::stoul(line.substr(idx), &end)};
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connections.insert({from, to});
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connections.insert({to, from});
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idx += end;
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}
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}
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VisitMap connected0;
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connected0.insert({0, InTree{}});
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while (true) {
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auto it{find_next_node(connected0)};
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if (it == connected0.end()) {
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break;
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}
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it->second.visit();
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auto [it_begin, it_end] = connections.equal_range(it->first);
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for (auto it2{it_begin}; it2 != it_end; ++it2) {
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connected0.insert({it2->second, InTree{}});
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}
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}
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std::cout << "Size of connected tree: " << connected0.size() << '\n';
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return 0;
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}
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