93 lines
2.1 KiB
C++
93 lines
2.1 KiB
C++
#include <algorithm>
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#include <cstdint>
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#include <iostream>
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#include <numeric>
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#include <sstream>
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#include <stdexcept>
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#include <string>
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#include <tuple>
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#include <vector>
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#include <doctest.h>
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#include <aocpp/Startup.hpp>
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namespace {
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using Input = std::vector<std::vector<std::int64_t>>;
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/// @brief Parse the input stream as a newline-delimited list of lists of integers
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/// @param in input file parsed until EOF
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/// @return outer list of elves, inner lists of calories
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auto Parse(std::istream & in) -> Input
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{
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Input result {{}};
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std::string line;
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while (std::getline(in, line)) {
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if (line.empty()) {
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result.push_back({});
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} else {
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result.back().emplace_back(std::stoll(line));
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}
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}
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return result;
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}
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/// @brief Compute the top calorie carrying elves
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/// @param input List of elves each with a list of calories
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/// @return top 1 and sum of top 3 calorie counts
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auto Solve(Input const& input) -> std::pair<std::int64_t, std::int64_t>
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{
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if (input.size() < 3) {
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throw std::runtime_error{"bad input"};
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}
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std::vector<std::int64_t> elves;
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std::transform(
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input.begin(), input.end(), std::back_inserter(elves),
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[](auto const& elf){
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return std::reduce(elf.begin(), elf.end());
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});
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// Fill the top 3 array elements with the maximum values
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auto const top3 = std::next(elves.begin(), 3);
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std::partial_sort(elves.begin(), top3, elves.end(), std::greater());
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auto const p1 = elves.front();
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auto const p2 = std::reduce(elves.begin(), top3);
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return {p1, p2};
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}
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} // namespace
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TEST_SUITE("2022-01 examples") {
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TEST_CASE("example") {
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std::istringstream in {
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"1000\n"
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"2000\n"
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"3000\n"
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"\n"
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"4000\n"
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"\n"
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"5000\n"
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"6000\n"
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"\n"
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"7000\n"
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"8000\n"
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"9000\n"
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"\n"
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"10000\n"};
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auto const entries = Parse(in);
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auto const [p1,p2] = Solve(entries);
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CHECK(p1 == 24000);
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CHECK(p2 == 45000);
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}
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}
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auto Main(std::istream & in) -> void
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{
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auto const [p1,p2] = Solve(Parse(in));
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std::cout << "Part 1: " << p1 << std::endl;
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std::cout << "Part 2: " << p2 << std::endl;
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}
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