Files
aoc/sol/24/day07.cpp
2024-12-16 04:03:02 +01:00

129 lines
4.4 KiB
C++

#include <vector>
#include <ranges>
#include <numeric>
#include "aoc.hpp"
#include "aoc/utils.hpp"
#include "fmt/format.h"
using namespace aoc::types;
using namespace std::string_view_literals;
namespace rbr {
enum class op {
add,
mul,
};
class expr {
public:
expr(u64 eres, std::vector<u64> const& operands)
: m_eres(eres), m_operands(operands) {
find_res();
}
auto find_res() -> bool {
auto const max = std::pow(2, m_operands.size());
for (u32 t = 0; t < max; ++t) {
m_ops = t;
m_res = 0;
compute();
if (m_res == m_eres) break;
}
return m_res == m_eres;
}
auto compute() -> void {
for (usize i = 0; i < m_operands.size(); ++i) {
if (i == 0) {
m_res = m_operands[0];
continue;
}
auto const a = m_res;
auto const b = m_operands[i];
auto const am = op((m_ops >> (i - 1)) & 0x01);
if (am == op::add)
m_res = a + b;
else
m_res = a * b;
}
}
auto res() const -> u64 { return m_eres; }
auto eres() const -> u64 { return m_eres; }
auto operands() const -> std::vector<u64> const& { return m_operands; }
auto ops() const -> u32 const& { return m_ops; }
auto valid() const -> bool { return m_res == m_eres; };
auto str() const -> std::string {
using namespace std::string_literals;
std::string str{"expr {"};
str += " expect: "s + std::to_string(m_eres) + ",";
str += " expr: "s;
str += std::to_string(m_res) + " = ";
for (usize i = 0; i < m_operands.size(); ++i) {
auto const& operand = m_operands[i + 0];
str += std::to_string(operand);
if (i == m_operands.size() - 1) break;
str += ((m_ops >> i) & 0x01) == 0x01 ? "+" : "*";
}
str += " }";
return str;
}
private:
u64 m_eres;
std::vector<u64> m_operands;
u64 m_res{0x00};
u32 m_ops{0x00};
};
auto str_to_op(std::string const& str) -> expr {
auto const splitc = str | std::views::split(": "sv)
| std::views::transform([](auto const& str){
return std::string(std::begin(str), std::end(str));
})
| std::views::filter([](auto const& str) { return !str.empty(); })
| std::ranges::to<std::vector>();
u64 const a = std::stoull(splitc[0]);
auto const b = splitc[1] | std::views::split(" "sv)
| std::views::transform([](auto const& str){
return std::string(std::begin(str), std::end(str));
})
| std::views::filter([](auto const& str) { return !str.empty(); })
| std::views::transform([](auto const& str) { return std::stoull(str); })
| std::ranges::to<std::vector>();
return {a, b};
}
}
auto aoc24::day07([[maybe_unused]]std::span<char const*> const& args) -> std::expected<void, aoc::error> {
// auto res = aoc::read_text("./dat/24/ex/07.txt");
auto res = aoc::read_text("./dat/24/re/07.txt");
if (!res) return std::unexpected(res.error());
auto const txt = *res;
auto exprs = txt | std::views::split("\n"sv)
| std::views::transform([](auto const& str){
return std::string(std::begin(str), std::end(str));
})
| std::views::filter([](auto const& str) { return !str.empty(); })
| std::views::transform(rbr::str_to_op);
auto const valids = exprs | std::views::filter([](auto const expr) { return expr.valid(); })
| std::views::transform([](auto const& e) { return f64(e.eres()); })
| std::ranges::to<std::vector>();
auto const sum = std::accumulate(std::begin(valids), std::end(valids), 0.0);
fmt::print("{}\n", sum);
// auto const validsex = exprs | std::views::filter([](auto const expr) { return !expr.valid(); })
// | std::ranges::to<std::vector>();
//
// for (auto const& exp : validsex) {
// fmt::print("{}\n", exp.str());
// }
return {};
}