133 lines
2.9 KiB
C++
133 lines
2.9 KiB
C++
#include <BAN/StringView.h>
|
|
#include <BAN/Vector.h>
|
|
|
|
#include <inttypes.h>
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
|
|
using i8 = int8_t;
|
|
using i16 = int16_t;
|
|
using i32 = int32_t;
|
|
using i64 = int64_t;
|
|
|
|
using u8 = uint8_t;
|
|
using u16 = uint16_t;
|
|
using u32 = uint32_t;
|
|
using u64 = uint64_t;
|
|
|
|
struct Grid2D
|
|
{
|
|
size_t width { 0 };
|
|
size_t height { 0 };
|
|
BAN::Vector<char> data;
|
|
};
|
|
|
|
static Grid2D read_grid2d(FILE* fp)
|
|
{
|
|
size_t width { 0 };
|
|
size_t height { 0 };
|
|
BAN::Vector<char> data;
|
|
|
|
char buffer[1024];
|
|
while (fgets(buffer, sizeof(buffer), fp))
|
|
{
|
|
const size_t len = strlen(buffer);
|
|
if (len == 0 || buffer[0] == '\n')
|
|
break;
|
|
if (data.empty())
|
|
width = len - 1;
|
|
height++;
|
|
|
|
ASSERT(buffer[width] == '\n');
|
|
|
|
if (data.capacity() < height * width)
|
|
MUST(data.reserve(2 * height * width));
|
|
|
|
MUST(data.resize(height * width));
|
|
memcpy(&data[(height - 1) * width], buffer, width);
|
|
}
|
|
|
|
(void)data.shrink_to_fit();
|
|
|
|
return Grid2D {
|
|
.width = width,
|
|
.height = height,
|
|
.data = BAN::move(data),
|
|
};
|
|
}
|
|
|
|
static bool check_match(const Grid2D& puzzle, size_t x, size_t y, i32 step_x, i32 step_y, BAN::StringView target)
|
|
{
|
|
if (i32 ex = (i32)x + step_x * (i32)(target.size() - 1); ex < 0 || ex >= (i32)puzzle.width)
|
|
return false;
|
|
if (i32 ey = (i32)y + step_y * (i32)(target.size() - 1); ey < 0 || ey >= (i32)puzzle.height)
|
|
return false;
|
|
for (size_t i = 0; i < target.size(); i++)
|
|
if (target[i] != puzzle.data[(y + i * step_y) * puzzle.width + (x + i * step_x)])
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
i64 part1(FILE* fp)
|
|
{
|
|
i64 result = 0;
|
|
|
|
auto puzzle = read_grid2d(fp);
|
|
for (size_t y = 0; y < puzzle.height; y++) {
|
|
for (size_t x = 0; x < puzzle.width; x++) {
|
|
result += check_match(puzzle, x, y, 1, 0, "XMAS"_sv);
|
|
result += check_match(puzzle, x, y, 0, 1, "XMAS"_sv);
|
|
result += check_match(puzzle, x, y, 1, 1, "XMAS"_sv);
|
|
result += check_match(puzzle, x, y, 1, -1, "XMAS"_sv);
|
|
|
|
result += check_match(puzzle, x, y, 1, 0, "SAMX"_sv);
|
|
result += check_match(puzzle, x, y, 0, 1, "SAMX"_sv);
|
|
result += check_match(puzzle, x, y, 1, 1, "SAMX"_sv);
|
|
result += check_match(puzzle, x, y, 1, -1, "SAMX"_sv);
|
|
}
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
i64 part2(FILE* fp)
|
|
{
|
|
i64 result = 0;
|
|
|
|
auto puzzle = read_grid2d(fp);
|
|
for (size_t y = 1; y < puzzle.height - 1; y++) {
|
|
for (size_t x = 1; x < puzzle.width - 1; x++) {
|
|
if (!check_match(puzzle, x - 1, y - 1, 1, 1, "MAS") && !check_match(puzzle, x - 1, y - 1, 1, 1, "SAM"))
|
|
continue;
|
|
if (!check_match(puzzle, x - 1, y + 1, 1, -1, "MAS") && !check_match(puzzle, x - 1, y + 1, 1, -1, "SAM"))
|
|
continue;
|
|
result++;
|
|
}
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
int main(int argc, char** argv)
|
|
{
|
|
const char* file_path = "/usr/share/aoc2024/day4_input.txt";
|
|
|
|
if (argc >= 2)
|
|
file_path = argv[1];
|
|
|
|
FILE* fp = fopen(file_path, "r");
|
|
if (fp == nullptr)
|
|
{
|
|
perror("fopen");
|
|
return 1;
|
|
}
|
|
|
|
printf("part1: %" PRId64 "\n", part1(fp));
|
|
|
|
fseek(fp, 0, SEEK_SET);
|
|
|
|
printf("part2: %" PRId64 "\n", part2(fp));
|
|
|
|
fclose(fp);
|
|
}
|