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#include <iostream>
#include <fstream>
#include <array>
#include <vector>
#include <unordered_map>
#include "util.h"
constexpr int FEATS = 4;
constexpr int MIN = 1 - 1;
constexpr int MAX = 4000 + 1;
using Name = std::string;
using Cond = std::tuple<char,char,int>;
using Rule = std::pair<std::vector<Cond>,Name>;
using Bounds = std::array<int,2*FEATS>;
using Workflows = std::unordered_map<Name,Rule>;
const std::unordered_map<char,int> fields{ {'x', 0}, {'m', 2}, {'a', 4}, {'s', 6} };
Cond neg(const Cond& cond)
{
auto [f,o,v] = cond;
return { f, (o == '<') ? '>' : '<', v + ((o == '<') ? -1 : 1) };
}
std::pair<std::vector<Rule>,Workflows> parse(const char* file)
{
using namespace util::separators;
Workflows workflows;
std::vector<Rule> arules;
if (std::ifstream input{ file }; input.is_open())
{
std::string line;
std::getline(input,line);
while (not line.empty())
{
auto bw = line.find('{');
Name next = line.substr(0, bw);
std::vector<std::pair<Cond,Name>> conds;
line = line.substr(bw + 1, line.size() - bw - 2);
for (auto srule : util::split<COMMA>(std::string_view{ line }))
{
auto tokens = util::split<COLON>(srule);
if (tokens.size() > 1)
{
int val = std::stoi(std::string(tokens[0].substr(2)));
conds.push_back({ { tokens[0][0], tokens[0][1], val }, Name{ tokens[1] } });
}
else
{
conds.push_back({ { 0, 0, 0 }, Name{ tokens[0] } });
}
}
for (int i = 0; i < conds.size(); ++i)
{
auto [cond, name] = conds[i];
if (name == "R") continue;
int j{ i - 1 };
auto [f,o,v] = cond;
std::vector<Cond> nconds;
nconds.push_back(f ? cond : neg(std::get<0>(conds[j--])));
for (; j >= 0; --j)
{
nconds.push_back(neg(std::get<0>(conds[j])));
}
if (name == "A")
{
arules.push_back({ std::move(nconds), next });
}
else
{
workflows.insert({ name, { std::move(nconds), next } });
}
}
std::getline(input,line);
}
}
return { std::move(arules), std::move(workflows) };
}
Bounds operator&&(const Bounds& a, const Bounds& b)
{
Bounds c;
for (int i = 0; i < FEATS; ++i)
{
c[2*i] = std::max(a[2*i], b[2*i]);
c[2*i+1] = std::min(a[2*i+1], b[2*i+1]);
}
return c;
}
void operator+=(Bounds& b, const Cond& c)
{
auto [f,o,v] = c;
int i{ fields.at(f) };
if (o == '>')
{
b[i] = std::max(b[i],v);
}
else
{
b[i + 1] = std::min(b[i + 1],v);
}
}
Bounds compute_bounds(const Workflows& wfs, const Rule& rule)
{
Bounds bounds{ MIN, MAX, MIN, MAX, MIN, MAX, MIN, MAX };
auto [conds, next] = rule;
for (const auto& cond : conds)
{
bounds += cond;
}
if (next == "in") return { bounds };
return bounds && compute_bounds(wfs, wfs.at(next));
}
long long combinations(const Bounds& bounds)
{
long long res{ 1 };
for (int i = 0; i < FEATS; ++i)
{
if (bounds[2*i] >= bounds[2*i+1]) return 0;
res *= bounds[2*i+1] - bounds[2*i] - 1;
}
return res;
}
int main(int argc, char* argv[])
{
long answer{};
auto [arules, workflows] = parse(argv[1]);
for (const auto& rule : arules)
{
answer += combinations(compute_bounds(workflows, rule));
}
std::cout << answer<< std::endl;
return 0;
}
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