You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
82 lines
1.5 KiB
82 lines
1.5 KiB
#include <vector>
|
|
#include <iostream>
|
|
#include <fstream>
|
|
#include <string>
|
|
#include <tuple>
|
|
|
|
#include <attrs.h>
|
|
|
|
using mod_table = std::vector<std::vector<bool> >;
|
|
|
|
mod_table read_input(const char* _input)
|
|
{
|
|
std::ifstream input(_input);
|
|
if(!input) {
|
|
std::cerr << "Failed to open file: " << _input << std::endl;
|
|
std::terminate();
|
|
}
|
|
mod_table output;
|
|
|
|
std::string str;
|
|
while(input)
|
|
{
|
|
if(!std::getline(input, str)) break;
|
|
std::vector<bool> ln(str.size());
|
|
int i=0;
|
|
for(const auto& chr : str)
|
|
{
|
|
switch(chr)
|
|
{
|
|
case '#': ln[i] = true; fall;
|
|
default: i++; break;
|
|
}
|
|
}
|
|
output.push_back(std::move(ln));
|
|
str.clear();
|
|
}
|
|
return output;
|
|
}
|
|
|
|
template<typename V>
|
|
inline std::size_t wrapping_index(const V& vec, std::size_t i)
|
|
{
|
|
return (i % vec.size());
|
|
}
|
|
|
|
std::size_t count_slope(const mod_table& table, std::size_t stepx, std::size_t stepy)
|
|
{
|
|
std::size_t x=0;
|
|
std::size_t r=0;
|
|
for(std::size_t y=0;y<table.size();y+=stepy, x+=stepx)
|
|
{
|
|
r += table[y][wrapping_index(table[y], x)] ? 1 : 0;
|
|
}
|
|
return r;
|
|
}
|
|
|
|
int main()
|
|
{
|
|
|
|
const mod_table table = read_input("input");
|
|
#ifdef PART2
|
|
const auto paths = {
|
|
std::tuple<std::size_t, std::size_t>(1, 1),
|
|
std::tuple<std::size_t, std::size_t>(3, 1),
|
|
std::tuple<std::size_t, std::size_t>(5, 1),
|
|
std::tuple<std::size_t, std::size_t>(7, 1),
|
|
std::tuple<std::size_t, std::size_t>(1, 2),
|
|
};
|
|
|
|
std::size_t r=1;
|
|
for(const auto& [x, y] : paths)
|
|
{
|
|
r*= count_slope(table, x, y);
|
|
}
|
|
#else
|
|
auto r = count_slope(table, 3, 1);
|
|
#endif
|
|
|
|
std::cout << r << std::endl;
|
|
return 0;
|
|
}
|