aoc25/day6/main.cpp

#include <algorithm>
#include <array>
#include <charconv>
#include <cstddef>
#include <expected>
#include <format>
#include <fstream>
#include <functional>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <mdspan>
#include <numeric>
#include <print>
#include <ranges>
#include <set>
#include <sstream>
#include <string>
#include <string_view>
#include <unordered_set>
#include <utility>
#include <vector>
struct ColumnData {
    std::vector<int> numbers;
    char op;
};

struct Diagram {
    std::vector<char> data;
    size_t width;
    size_t height;

    using GridView = std::mdspan<char, std::dextents<size_t, 2>>;

    auto grid() { return GridView(data.data(), height, width); }
};

auto printDiagram(Diagram &diagram) {
    auto grid = diagram.grid();
    for (auto row = 0UZ; row != grid.extent(0); row++) {
        for (auto col = 0UZ; col != grid.extent(1); col++) {
            std::print("{}", grid[row, col]);
        }
        std::println();
    }
    // std::println("Map: {}", diagram.data);
    std::println("Width: {}", diagram.width);
    std::println("Height: {}", diagram.height);
}

template <typename T> auto parseLine(std::string_view line) -> std::vector<T> {
    auto to_value = [](auto &&subrange) -> T {
        auto str = std::string_view(subrange);
        T value{};
        if constexpr (std::is_same_v<T, char>) {
            return str[0];
        } else {
            std::from_chars(str.data(), str.data() + str.size(), value);
            return value;
        }
    };

    return line | std::views::split(' ') | std::views::filter([](auto &&range) -> bool { return !range.empty(); }) |
           std::views::transform(to_value) | std::ranges::to<std::vector<T>>();
}

static auto parseInput(const std::string &filename) -> std::expected<std::vector<ColumnData>, std::string> {
    std::ifstream inputF{filename};

    if (!inputF) {
        return std::unexpected{"Some file open error."};
    }
    std::vector<ColumnData> puzzleInput{};

    std::vector<std::string> rawLines;
    std::string puzzleLine;
    while (std::getline(inputF, puzzleLine)) {
        if (!puzzleLine.empty()) {
            rawLines.push_back(std::move(puzzleLine));
        }
    }
    if (rawLines.empty()) {
        return std::unexpected{"No lines."};
    }

    auto operatorLine = rawLines.back();
    auto num_lines = rawLines | std::views::take(rawLines.size() - 1);

    std::vector<char> ops = parseLine<char>(operatorLine);

    auto grid =
        num_lines |
        std::views::transform([](const std::string &string) -> std::vector<int> { return parseLine<int>(string); }) |
        std::ranges::to<std::vector<std::vector<int>>>();

    size_t width = ops.size();
    bool consistent = std::ranges::all_of(grid, [width](const auto &row) -> bool { return row.size() == width; });
    if (!consistent) {
        return std::unexpected{"Error: Row width mismatch."};
    }

    auto columns = std::views::iota(0UZ, width) | std::views::transform([&](size_t col_idx) -> ColumnData {
                       // Collect numbers for this column from the grid
                       auto col_nums = grid |
                                       std::views::transform([col_idx](const auto &row) { return row[col_idx]; }) |
                                       std::ranges::to<std::vector<int>>();

                       return ColumnData{.numbers = std::move(col_nums), .op = ops[col_idx]};
                   }) |
                   std::ranges::to<std::vector<ColumnData>>();
    std::cout << "Parsed " << columns.size() << " columns with " << grid.size() << " operands each:\n";

    for (const auto &col : columns) {
        std::cout << "[ ";
        for (int n : col.numbers) {
            std::cout << n << " ";
        }
        std::cout << "] Op: " << col.op << "\n";
    }
    return std::move(columns);
}

static auto parseInput_p2(const std::string &filename) -> std::expected<Diagram, std::string> {
    std::ifstream inputF{filename};

    if (!inputF) {
        return std::unexpected{"Some file open error."};
    }
    Diagram puzzleInput{};
    int maxWidth = 0;
    std::string puzzleLine;
    while (std::getline(inputF, puzzleLine)) {
        if (!puzzleLine.empty()) {
            std::ranges::reverse(puzzleLine);
            for (auto c : puzzleLine) {
                puzzleInput.data.emplace_back(c);
            }
            puzzleInput.width = puzzleLine.length();
            puzzleInput.height++;
        }
    }

    std::println("{}", puzzleInput.data);
    printDiagram(puzzleInput);
    return puzzleInput;
}

auto calculate_column(const ColumnData &col) -> long long {
    if (col.op == '+') {
        return std::ranges::fold_left(col.numbers, 0LL, std::plus());
    }
    if (col.op == '*') {
        return std::ranges::fold_left(col.numbers, 1LL, std::multiplies());
    }
    return 0; // Fallback
}

auto cephalopodMath(const std::vector<ColumnData> &columns) -> long long {
    long long grand_total = std::ranges::fold_left(columns | std::views::transform(calculate_column), 0LL, std::plus{});
    return grand_total;
}
auto cephalopodMath_p2(Diagram &diagram) -> long long {
    long long grandTotal{};

    long long currentNumber = 0;
    std::vector<long long> columnNumbers{};
    auto grid = diagram.grid();
    for (auto col = 0UZ; col != grid.extent(1); col++) {
        for (auto row = 0UZ; row != grid.extent(0); row++) {
            char cur = grid[row, col];

            if (cur == ' ' && currentNumber == 0) {
                // std::print("s");
                continue;
            } else if (cur == ' ') {
                columnNumbers.emplace_back(currentNumber);
                currentNumber = 0;
                std::print("_");
                continue;
            } else if (cur == '*') {
                if (currentNumber != 0) {
                    columnNumbers.emplace_back(currentNumber);
                }
                std::print("*");
                auto total = std::ranges::fold_left(columnNumbers, 1LL, std::multiplies());
                grandTotal += total;
                std::print("\nMultiplying {}: Result: {}\n", columnNumbers, total);
                currentNumber = 0;
                columnNumbers.clear();
                continue;
            } else if (cur == '+') {
                if (currentNumber != 0) {
                    columnNumbers.emplace_back(currentNumber);
                }
                std::print("+");
                auto total = std::ranges::fold_left(columnNumbers, 0LL, std::plus());
                grandTotal += total;
                std::print("\nAdding {}: Result: {}\n", columnNumbers, total);

                currentNumber = 0;
                columnNumbers.clear();
                continue;
            }

            // cur must be a digit...
            currentNumber = (currentNumber * 10) + (cur - '0');
            std::print("{}", cur);
        }
    }
    return grandTotal;
}

auto main() -> int {
    // auto testCase = parseInput("test_input");
    // if (testCase) {

    //     auto testResult = cephalopodMath(*testCase);
    //     std::println("P1 Testcase result: {}", testResult);
    // } else {
    //     std::print("{}\n", testCase.error());
    // }

    auto testCase_p2 = parseInput_p2("test_input");
    if (testCase_p2) {
        auto testResult_p2 = cephalopodMath_p2(*testCase_p2);
        std::println("P2 Testcase result: {}", testResult_p2);
    } else {
        std::print("{}\n", testCase_p2.error());
    }

    auto realPuzzle = parseInput_p2("puzzle_input");
    if (realPuzzle) {
        // auto realResult = cephalopodMath(*realPuzzle);
        // std::println("P1 Real result: {}", realResult);

        auto realResultP2 = cephalopodMath_p2(*realPuzzle);
        std::println("P2 Real result: {}", realResultP2);
    } else {
        std::print("{}\n", realPuzzle.error());
    }

    return 0;
}