banan-os/userspace/aoc2023/day25/main.cpp

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#include <BAN/HashMap.h>
#include <BAN/HashSet.h>
#include <BAN/Sort.h>
#include <BAN/String.h>
#include <BAN/Vector.h>
#include <ctype.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.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 Component
{
Component(BAN::String name)
: name(BAN::move(name))
{}
BAN::String name;
BAN::Vector<BAN::String> connections;
};
BAN::HashMap<BAN::String, Component> parse_components(FILE* fp)
{
BAN::HashMap<BAN::String, Component> components;
char buffer[128];
while (fgets(buffer, sizeof(buffer), fp))
{
BAN::StringView line(buffer);
ASSERT(line.back() == '\n');
line = line.substring(0, line.size() - 1);
if (line.empty())
break;
auto parts = MUST(line.split(' '));
ASSERT(parts.size() >= 2);
ASSERT(parts.front().back() == ':');
parts.front() = parts.front().substring(0, parts.front().size() - 1);
if (!components.contains(parts.front()))
MUST(components.emplace(parts.front(), parts.front()));
for (size_t i = 1; i < parts.size(); i++)
{
MUST(components[parts.front()].connections.emplace_back(parts[i]));
if (!components.contains(parts[i]))
MUST(components.emplace(parts[i], parts[i]));
MUST(components[parts[i]].connections.emplace_back(parts.front()));
}
}
return components;
}
BAN::String connection_key(const BAN::String& a, const BAN::String& b)
{
auto comp =
[](const auto& a, const auto& b)
{
ASSERT(a.size() == b.size());
for (size_t i = 0; i < a.size(); i++)
if (a[i] != b[i])
return a[i] < b[i];
ASSERT_NOT_REACHED();
};
const auto& s1 = comp(a, b) ? a : b;
const auto& s2 = comp(a, b) ? b : a;
auto key = s1;
MUST(key.append(s2));
return key;
}
size_t graph_size(const BAN::HashMap<BAN::String, Component>& graph, const BAN::String& start, const BAN::HashSet<BAN::String>& removed)
{
BAN::HashSet<BAN::String> visited;
BAN::HashSet<BAN::String> pending;
MUST(pending.insert(start));
while (!pending.empty())
{
auto current = *pending.begin();
pending.remove(current);
MUST(visited.insert(current));
const auto& targets = graph[current].connections;
for (const auto& target : targets)
{
if (removed.contains(connection_key(current, target)))
continue;
if (visited.contains(target))
continue;
MUST(pending.insert(target));
MUST(visited.insert(target));
}
}
return visited.size();
}
BAN::Vector<BAN::String> find_shortest_path(const BAN::String& start, const BAN::String& end, const BAN::HashMap<BAN::String, Component>& graph)
{
BAN::HashMap<BAN::String, BAN::Vector<BAN::String>> paths;
MUST(paths.insert(start, {}));
MUST(paths[start].push_back(start));
BAN::HashSet<BAN::String> visited;
BAN::HashSet<BAN::String> pending;
MUST(pending.insert(start));
while (!pending.empty())
{
BAN::HashSet<BAN::String> next_pending;
while (!pending.empty())
{
auto current = *pending.begin();
pending.remove(current);
MUST(visited.insert(current));
if (current == end)
return paths[current];
const auto& targets = graph[current].connections;
for (const auto& target : targets)
{
if (visited.contains(target))
continue;
if (pending.contains(target))
continue;
if (next_pending.contains(target))
continue;
if (paths.contains(target))
continue;
MUST(next_pending.insert(target));
MUST(visited.insert(target));
MUST(paths.insert(target, paths[current]));
MUST(paths[target].push_back(target));
}
}
pending = BAN::move(next_pending);
}
ASSERT_NOT_REACHED();
}
i64 puzzle1(FILE* fp)
{
auto components = parse_components(fp);
BAN::HashMap<BAN::String, i64> connection_count;
srand(time(nullptr));
for (size_t i = 0; i < 100; i++)
{
size_t idx1 = rand() % components.size();
size_t idx2 = rand() % components.size();
auto path = find_shortest_path(next(components.begin(), idx1)->key, next(components.begin(), idx2)->key, components);
for (size_t j = 1; j < path.size(); j++)
{
const auto& connection = connection_key(path[j - 1], path[j]);
if (!connection_count.contains(connection))
MUST(connection_count.insert(connection, 0));
connection_count[connection]++;
}
}
struct Connection
{
BAN::String connection;
i64 count;
};
BAN::Vector<Connection> hot_connections;
for (const auto& [connection, count] : connection_count)
MUST(hot_connections.emplace_back(connection, count));
BAN::sort::sort(hot_connections.begin(), hot_connections.end(), [](const auto& a, const auto& b) { return a.count > b.count; });
for (size_t depth = 0; depth < hot_connections.size(); depth++)
{
for (size_t i = 0; i < depth; i++)
{
for (size_t j = i + 1; j < depth; j++)
{
for (size_t k = j + 1; k < depth; k++)
{
BAN::HashSet<BAN::String> removed;
MUST(removed.insert(hot_connections[i].connection));
MUST(removed.insert(hot_connections[j].connection));
MUST(removed.insert(hot_connections[k].connection));
size_t lhs_size = graph_size(components, hot_connections[i].connection.sv().substring(0, 3), removed);
if (lhs_size == components.size())
continue;
size_t rhs_size = graph_size(components, hot_connections[i].connection.sv().substring(3, 3), removed);
if (rhs_size == components.size())
continue;
if (lhs_size + rhs_size == components.size())
return lhs_size * rhs_size;
}
}
}
}
return -1;
}
i64 puzzle2(FILE* fp)
{
(void)fp;
return -1;
}
int main(int argc, char** argv)
{
const char* file_path = "/usr/share/aoc2023/day25_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);
}