banan-os/userspace/aoc2023/day12/main.cpp

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#include <BAN/HashMap.h>
#include <BAN/String.h>
#include <BAN/Swap.h>
#include <BAN/Vector.h>
#include <ctype.h>
#include <inttypes.h>
#include <stdio.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;
u64 parse_u64(BAN::StringView str)
{
u64 result = 0;
for (char c : str)
if (isdigit(c))
result = (result * 10) + (c - '0');
return result;
}
static BAN::HashMap<BAN::String, i64> s_cache;
BAN::String build_cache_key(BAN::StringView record, BAN::Span<u64> groups)
{
BAN::String cache_key;
MUST(cache_key.append(record));
for (u64 group : groups)
MUST(cache_key.append(BAN::String::formatted(" {}", group)));
return cache_key;
}
i64 count_possibilities(BAN::StringView record, BAN::Span<u64> groups)
{
if (groups.empty())
return !record.contains('#');
if (record.empty())
return 0;
auto cache_key = build_cache_key(record, groups);
if (s_cache.contains(cache_key))
return s_cache[cache_key];
i64 result = 0;
for (size_t i = 0; i + groups[0] <= record.size(); i++)
{
bool valid = true;
if (record.substring(i, groups[0]).contains('.'))
valid = false;
if (i + groups[0] < record.size() && record[i + groups[0]] == '#')
valid = false;
if (valid)
{
auto next_record = record.substring(i + groups[0]);
if (!next_record.empty())
next_record = next_record.substring(1);
result += count_possibilities(next_record, groups.slice(1));
}
if (record[i] == '#')
break;
}
//printf("inserting... "); fflush(stdout);
MUST(s_cache.insert(cache_key, result));
//printf("done\n");
return result;
}
i64 puzzle1(FILE* fp)
{
i64 result = 0;
char buffer[128];
while (fgets(buffer, sizeof(buffer), fp))
{
BAN::StringView line(buffer);
if (line.back() == '\n')
line = line.substring(0, line.size() - 1);
if (line.size() < 3)
continue;
auto parts = MUST(line.split(' '));
auto record = parts[0];
auto continuous_strs = MUST(parts[1].split(','));
BAN::Vector<u64> continuous(continuous_strs.size());
for (size_t i = 0; i < continuous.size(); i++)
continuous[i] = parse_u64(continuous_strs[i]);
result += count_possibilities(record, continuous.span());
}
return result;
}
i64 puzzle2(FILE* fp)
{
i64 result = 0;
char buffer[128];
while (fgets(buffer, sizeof(buffer), fp))
{
BAN::StringView line(buffer);
if (line.back() == '\n')
line = line.substring(0, line.size() - 1);
if (line.size() < 3)
continue;
auto parts = MUST(line.split(' '));
BAN::String record;
MUST(record.reserve(parts[0].size() + 4));
for (size_t i = 0; i < 5; i++)
{
if (i > 0)
MUST(record.push_back('?'));
MUST(record.append(parts[0]));
}
auto continuous_strs = MUST(parts[1].split(','));
BAN::Vector<u64> continuous(5 * continuous_strs.size());
for (size_t i = 0; i < continuous.size(); i++)
continuous[i] = parse_u64(continuous_strs[i % continuous_strs.size()]);
result += count_possibilities(record, continuous.span());
}
return result;
}
int main(int argc, char** argv)
{
const char* file_path = "/usr/share/aoc2023/day12_input.txt";
if (argc >= 2)
file_path = argv[1];
FILE* fp = fopen(file_path, "r");
if (fp == nullptr)
{
perror("fopen");
return 1;
}
printf("puzzle1: %" PRId64 "\n", puzzle1(fp));
fseek(fp, 0, SEEK_SET);
printf("puzzle2: %" PRId64 "\n", puzzle2(fp));
fclose(fp);
}