96 lines
2.1 KiB
C++
96 lines
2.1 KiB
C++
//
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// Created by Matthew Gretton-Dann on 16/12/2022.
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//
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#include <array>
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#include <iostream>
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#include <map>
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#include <numeric>
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#include <stdexcept>
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#include <utility>
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using Int = std::int64_t;
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using UInt = std::uint64_t;
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using Ints = std::vector<std::pair<Int, Int>>;
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using namespace std::string_literals;
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struct Monkey
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{
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Monkey() = default;
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explicit Monkey(Int value) : value_(value), value_known_(true) {}
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Monkey(std::string lhs, char op, std::string rhs)
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: lhs_(std::move(lhs)), rhs_(std::move(rhs)), op_(op)
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{
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}
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Monkey(Monkey const&) = default;
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Monkey(Monkey&&) = default;
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auto operator=(Monkey const&) -> Monkey& = default;
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auto operator=(Monkey&&) -> Monkey& = default;
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~Monkey() = default;
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Int value_{0};
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bool value_known_{false};
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std::string lhs_;
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std::string rhs_;
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char op_{'\0'};
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};
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auto calculate(Int lhs, char op, Int rhs)
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{
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switch (op) {
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case '+':
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return lhs + rhs;
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case '-':
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return lhs - rhs;
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case '*':
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return lhs * rhs;
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case '/':
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return lhs / rhs;
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default:
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std::abort();
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}
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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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std::map<std::string, Monkey> monkies;
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while (std::getline(std::cin, line)) {
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std::string const id(line.substr(0, 4));
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if (std::isdigit(line[6]) != 0) {
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auto [it, success] = monkies.insert({id, Monkey(std::stoll(line.substr(6)))});
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assert(success);
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}
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else {
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auto [it, success] =
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monkies.insert({id, Monkey(line.substr(6, 4), line[11], line.substr(13))});
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assert(success);
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}
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}
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while (!monkies["root"s].value_known_) {
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for (auto& monkey : monkies) {
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if (monkey.second.value_known_) {
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continue;
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}
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auto lhs = monkies.find(monkey.second.lhs_);
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auto rhs = monkies.find(monkey.second.rhs_);
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if (!lhs->second.value_known_ || !rhs->second.value_known_) {
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continue;
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}
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monkey.second.value_ = calculate(lhs->second.value_, monkey.second.op_, rhs->second.value_);
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monkey.second.value_known_ = true;
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}
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}
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std::cout << "Root's value: " << monkies["root"s].value_ << "\n";
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return EXIT_SUCCESS;
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}
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