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#include <fstream>
#include <iostream>
#include <map>
#include <vector>
#include <cmath>
using Schematic = std::vector<std::string>;
using Gears = std::map<std::pair<int,int>,std::vector<int>>;
void check(const Schematic& schematic, Gears& gears, int num, int x, int y)
{
if (x >= 0 and y >= 0 and x < schematic.size()
and y < schematic[x].size() and schematic[x][y] == '*')
{
std::pair<int,int> key{ x, y };
if (not gears.count(key))
{
gears.insert({key, std::vector<int>{}});
}
gears[key].push_back(num);
}
}
void check_gears(const Schematic& schematic, Gears& gears, int num, int x, int y)
{
int len = 1 + static_cast<int>(std::log10(num));
check(schematic, gears, num, x - 1, y - len - 1);
check(schematic, gears, num, x, y - len - 1);
check(schematic, gears, num, x + 1, y - len - 1);
for (int a = 1; a <= len; ++a)
{
check(schematic, gears, num, x - 1, y - a);
check(schematic, gears, num, x + 1, y - a);
}
check(schematic, gears, num, x - 1, y);
check(schematic, gears, num, x, y);
check(schematic, gears, num, x + 1, y);
}
Gears find_gears(const Schematic& schematic)
{
Gears gears;
for (int x = 0; x < schematic.size(); ++x)
{
const std::string& line = schematic[x];
int cur{};
for (int y = 0; y < line.size(); ++y)
{
if (std::isdigit(line[y]))
{
cur = 10 * cur + (line[y] - '0');
}
else
{
if (cur > 0)
{
check_gears(schematic, gears, cur, x, y);
}
cur = 0;
}
}
}
return gears;
}
int main(void)
{
int answer{};
Schematic schematic{};
std::ifstream input{ "resources/input.txt" };
if (input.is_open())
{
std::string line;
while (not std::getline(input,line).eof())
{
line.push_back('.');
schematic.push_back(std::move(line));
}
}
input.close();
Gears gears = find_gears(schematic);
for (const auto& [_, vals] : gears) {
if (vals.size() == 2)
{
answer += vals[0] * vals[1];
}
}
std::cout << answer << std::endl;
return 0;
}
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