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#include <cstddef>
#include <fstream>
#include <iostream>
#include <set>
#include <string>
#include <vector>
using namespace std;
vector<string>
read_file(string_view filename)
{
fstream input{ filename };
vector<string> data;
for ( string line; getline(input, line); ) {
data.emplace_back(line);
}
return data;
}
void
part1(const vector<string>& data)
{
set<tuple<size_t, size_t>> positions;
char max_so_far = 0;
auto update = [&](size_t row, size_t col) {
if ( data[row][col] > max_so_far ) {
positions.emplace(row, col);
max_so_far = data[row][col];
}
};
for ( size_t row = 0; row != data.size(); ++row ) {
max_so_far = 0;
for ( size_t col = 0; col != data[row].size(); ++col ) {
update(row, col);
}
max_so_far = 0;
for ( size_t col = data[row].size(); col-- > 0; ) {
update(row, col);
}
}
for ( size_t col = 0; col != data[0].size(); ++col ) {
max_so_far = 0;
for ( size_t row = 0; row != data.size(); ++row ) {
update(row, col);
}
max_so_far = 0;
for ( size_t row = data.size(); row-- > 0; ) {
update(row, col);
}
}
cout << positions.size() << endl;
}
void
part2(const vector<string>& data)
{
auto check = [&](size_t row, size_t col) -> size_t {
size_t mul = 1;
const tuple<size_t, size_t> directions[] = { { -1, 0 }, { 1, 0 }, { 0, -1 }, { 0, 1 } };
for ( const auto& [dr, dc]: directions ) {
size_t step = 1;
for ( ;; ++step ) {
const auto nrow = row + step * dr;
const auto ncol = col + step * dc;
if (nrow >= data.size() || ncol >= data[row].size()) {
--step;
break;
}
if (data[nrow][ncol] >= data[row][col]) {
break;
}
}
mul *= step;
}
return mul;
};
size_t max_so_far = 0;
for ( size_t row = 0; row != data.size(); ++row ) {
for ( size_t col = 0; col != data[row].size(); ++col ) {
max_so_far = max(max_so_far, check(row, col));
}
}
cout << max_so_far << endl;
}
int
main()
{
const auto grid = read_file("data/day08.txt");
part1(grid);
part2(grid);
}
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