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#include <iostream>
#include <fstream>
#include <sstream>
#include <deque>
#include <vector>
#include <tuple>
#include "util.h"
using Cmd = std::tuple<char,int>;
using Pos = std::pair<int,int>;
using Polygon = std::vector<Pos>;
std::vector<Cmd> parse(const char* file)
{
std::vector<Cmd> cmds;
if (std::ifstream input{ file }; input.is_open())
{
char dir; int steps;
std::string line;
while (not std::getline(input,line).eof())
{
std::stringstream in{ line };
in >> dir >> steps;
cmds.push_back({ dir, steps });
}
}
return cmds;
}
std::pair<int,Polygon> compute_border(Pos pos, const std::vector<Cmd>& cmds)
{
Polygon poly;
int border{};
auto [x, y] = pos;
for(const auto& cmd : cmds)
{
auto [dir, steps] = cmd;
switch (dir)
{
case 'R': y += steps; break;
case 'D': x += steps; break;
case 'L': y -= steps; break;
case 'U': x -= steps;
}
poly.push_back({ x, y });
border += steps;
}
return { border, std::move(poly) };
}
int main(int argc, char* argv[])
{
auto cmds = parse(argv[1]);
auto [border, polygon] = compute_border({ 0, 0 }, cmds);
int area = util::shoelace<int>(polygon.cbegin(), polygon.cend());
std::cout << border + util::pick(area, border) << std::endl;
return 0;
}
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