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#include <fstream>
#include <iostream>
#include <map>
#include <string>
#include <tuple>
using namespace std;
map<tuple<size_t, size_t>, char>
read_file(string_view filename)
{
fstream input{ filename };
map<tuple<size_t, size_t>, char> data;
size_t yPos = 0;
for ( string line; getline(input, line); ) {
for ( size_t xPos = 0; xPos != line.size(); ++xPos ) {
data[{ xPos, yPos }] = line[xPos];
}
++yPos;
}
return data;
}
void
part1(map<tuple<size_t, size_t>, char> data, size_t size)
{
static const tuple<size_t, size_t> dirs[] = {
{ -1, -1 },
{ 0, -1 },
{ 1, -1 },
{ 1, 0 },
{ 1, 1 },
{ 0, 1 },
{ -1, 1 },
{ -1, 0 },
};
long count = 0;
for ( size_t y = 0; y != size; ++y ) {
for ( size_t x = 0; x != size; ++x ) {
for ( const auto& [dx, dy]: dirs ) {
if ( data[{ x, y }] == 'X' &&
data[{ x + 1 * dx, y + 1 * dy }] == 'M' &&
data[{ x + 2 * dx, y + 2 * dy }] == 'A' &&
data[{ x + 3 * dx, y + 3 * dy }] == 'S' ) {
++count;
}
}
}
}
cout << count << endl;
}
void
part2(map<tuple<size_t, size_t>, char> data, size_t size)
{
long count = 0;
for ( size_t y = 0; y != size; ++y ) {
for ( size_t x = 0; x != size; ++x ) {
if ( data[{ x, y }] == 'A' &&
data[{ x - 1, y - 1 }] == 'M' &&
data[{ x - 1, y + 1 }] == 'M' &&
data[{ x + 1, y - 1 }] == 'S' &&
data[{ x + 1, y + 1 }] == 'S' ) {
++count;
}
if ( data[{ x, y }] == 'A' &&
data[{ x - 1, y - 1 }] == 'S' &&
data[{ x - 1, y + 1 }] == 'M' &&
data[{ x + 1, y - 1 }] == 'S' &&
data[{ x + 1, y + 1 }] == 'M' ) {
++count;
}
if ( data[{ x, y }] == 'A' &&
data[{ x - 1, y - 1 }] == 'S' &&
data[{ x - 1, y + 1 }] == 'S' &&
data[{ x + 1, y - 1 }] == 'M' &&
data[{ x + 1, y + 1 }] == 'M' ) {
++count;
}
if ( data[{ x, y }] == 'A' &&
data[{ x - 1, y - 1 }] == 'M' &&
data[{ x - 1, y + 1 }] == 'S' &&
data[{ x + 1, y - 1 }] == 'M' &&
data[{ x + 1, y + 1 }] == 'S' ) {
++count;
}
}
}
cout << count << endl;
}
int
main()
{
auto data = read_file("data/day04.txt");
part1(data, 140);
part2(data, 140);
}
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