69 lines
2.0 KiB
C++
69 lines
2.0 KiB
C++
#include <numeric>
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#include <algorithm>
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#include "aoc.hpp"
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#include "aoc/utils.hpp"
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#include "fmt/format.h"
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auto aoc24::day01([[maybe_unused]]std::span<char const*> const& args) -> std::expected<void, aoc::error> {
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constexpr auto filename = "./dat/24/re/01.txt";
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std::ifstream strm{filename, std::ios::in};
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if (!strm.is_open()) {
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return aoc::make_error(
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fmt::format("Error opening file: {}\n", filename),
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std::errc::file_exists
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);
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}
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std::vector<std::uint32_t> a{};
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std::vector<std::uint32_t> b{};
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std::string str{};
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while (strm) {
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auto const c = char(strm.peek());
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if (std::isdigit(c)) {
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str += char(strm.get());
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continue;
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}
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if (c == ' ') {
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if (!str.empty()) {
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a.emplace_back(std::stoi(str));
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str.clear();
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}
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}
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if (c == '\n') {
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if (!str.empty()) {
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b.emplace_back(std::stoi(str));
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str.clear();
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}
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}
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[[discard]]strm.get();
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}
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fmt::print("a: {}, b: {}\n", a.size(), b.size());
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std::sort(std::begin(a), std::end(a));
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std::sort(std::begin(b), std::end(b));
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auto diff_view = std::views::zip(a, b) | std::views::transform([](auto const& p) {
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auto const [x, y] = p;
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return x > y ? x - y : y - x;
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});
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auto const sum = std::accumulate(std::begin(diff_view), std::end(diff_view), 0);
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fmt::print("Part A: {}\n", std::abs(sum));
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auto values = a | std::views::transform([&b](auto v) {
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return std::pair{v, b | std::views::filter([v](auto c) {
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return v == c; // Filter elements in `b` equal to `v`
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}) | std::ranges::to<std::vector>()};
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}) | std::ranges::to<std::vector>();
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auto const meow = std::accumulate(std::begin(values), std::end(values), 0, [](auto const acc, auto const& pair) {
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return acc + std::int32_t(pair.first * pair.second.size());
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});
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fmt::print("Part B: {}\n", meow);
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return {};
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}
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