90 lines
2.3 KiB
C++
90 lines
2.3 KiB
C++
#include <algorithm>
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#include <cassert>
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#include <iostream>
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#include <list>
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#include <map>
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#include <regex>
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#include <string>
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// This code is horrible - my only excuse is I wrote it before breakfast
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using Node = std::string;
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using Edge = std::pair<Node, Node>;
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using Weight = unsigned;
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using EdgeWeights = std::map<Edge, Weight>;
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struct BagGraph
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{
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void add_edges(std::string const& s)
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{
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static const auto prefix_re = std::regex("([a-z ]+) bags? contain ");
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static const auto suffix_re = std::regex("(\\d)+ ([a-z ]+) bags?[,.]\\s*");
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static const auto empty_str = std::string("no other bags.");
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std::smatch prefix_m;
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if (!std::regex_search(s, prefix_m, prefix_re)) {
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std::cout << "Failed to match: " << s << "\n";
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assert(false);
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return;
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}
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std::string n1 = prefix_m.str(1);
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std::string suffix = prefix_m.suffix();
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while (!suffix.empty()) {
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if (suffix == empty_str) {
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std::cout << n1 << " -> none: <empty>\n";
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suffix.clear();
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}
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else {
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std::smatch suffix_m;
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if (!std::regex_search(suffix, suffix_m, suffix_re)) {
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std::cout << "Failed to match: " << suffix << "\n";
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assert(false);
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return;
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}
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Weight w = std::stoul(suffix_m.str(1));
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Node n2 = suffix_m.str(2);
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suffix = suffix_m.suffix();
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Edge e = std::make_pair(n1, n2);
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edges_.insert({e, w});
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std::cout << n1 << " -> " << n2 << ": " << w << "\n";
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}
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}
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}
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Weight num_contained(Node const& n)
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{
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// Get the number of bags including the node we've been asked for so the
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// result is 1 less than the internal result
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return num_contained1(n) - 1;
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}
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private:
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Weight num_contained1(Node const& n)
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{
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Weight w = 0;
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bool contains_something = false;
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for (auto const& kv : edges_) {
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if (kv.first.first == n) {
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w += kv.second * num_contained1(kv.first.second);
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contains_something = true;
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}
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}
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return w + 1;
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}
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EdgeWeights edges_;
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};
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int main(int argc, char** argv)
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{
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BagGraph bg;
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for (std::string line; std::getline(std::cin, line);) {
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bg.add_edges(line);
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}
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Node n = "shiny gold";
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auto contained = bg.num_contained(n);
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std::cout << n << " contains " << contained << " bags.\n";
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return 0;
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} |