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#include <filesystem>
#include <fstream>
#include <iostream>
#include <numeric>
#include <sstream>
#include <string>
#include <vector>
using namespace std;
namespace {
using Grid = vector<vector<long>>;
using Ops = vector<char>;
vector<string>
read_file(const filesystem::path& filename)
{
ifstream file{ filename };
vector<string> lines;
for ( string line; getline(file, line); ) {
lines.emplace_back(line);
}
return lines;
}
Ops
read_ops(const string& line)
{
stringstream strm{ line };
Ops ops;
for ( char chr{}; strm >> chr; ) {
ops.emplace_back(chr);
}
return ops;
}
Ops
extract_ops(vector<string>& lines)
{
auto ops = read_ops(lines.back());
ranges::reverse(ops);
lines.pop_back();
return ops;
}
template<typename Matrix>
Matrix
rotateLeft90(const Matrix& matrix)
{
using Row = typename Matrix::value_type;
using T = typename Row::value_type;
if ( matrix.empty() ) {
return Matrix{};
}
const size_t rows = matrix.size();
const size_t cols = matrix[0].size();
Matrix result(cols, Row(rows, T{}));
for ( size_t row = 0; row != rows; ++row ) {
for ( size_t col = 0; col != cols; ++col ) {
result[cols - 1 - col][row] = matrix[row][col];
}
}
return result;
}
long
calculate(const Grid& grid, const Ops& ops)
{
long sum = 0;
for ( size_t row = 0; row != ops.size(); ++row ) {
const auto& line = grid[row];
if ( ops[row] == '*' ) {
sum += accumulate(line.begin(), line.end(), 1L, multiplies<>());
}
else {
sum += accumulate(line.begin(), line.end(), 0L);
}
}
return sum;
}
void
part1(vector<string> lines)
{
const auto ops = extract_ops(lines);
Grid grid;
grid.reserve(lines.size());
for ( const auto& line: lines ) {
stringstream strm{ line };
vector<long> numbers;
for ( long number{}; strm >> number; ) {
numbers.emplace_back(number);
}
grid.emplace_back(numbers);
}
grid = rotateLeft90(grid);
cout << "Part 1: " << calculate(grid, ops) << '\n';
}
void
part2(vector<string> lines)
{
const auto ops = extract_ops(lines);
lines = rotateLeft90(lines);
lines.emplace_back("");
Grid grid;
vector<long> curr;
for ( const auto& line: lines ) {
if ( long number{}; sscanf(line.data(), "%ld", &number) == 1 ) {
curr.emplace_back(number);
}
else {
grid.emplace_back(curr);
curr.clear();
}
}
cout << "Part 2: " << calculate(grid, ops) << '\n';
}
} // namespace
int
main()
{
const auto lines = read_file("data/day06.txt");
part1(lines);
part2(lines);
}
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