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Add 2017 Day 21 puzzles

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Matthew Gretton-Dann
2021-12-21 14:04:46 +00:00
parent 3e718e2aa0
commit 7d0fb91103
2 changed files with 284 additions and 0 deletions
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#include <cassert>
#include <iostream>
#include <map>
#include <regex>
#include <string>
[[nodiscard]] auto rotate(std::string const& s) -> std::string
{
if (s.size() == 4) {
return std::string{s[2], s[0], s[3], s[1]};
}
if (s.size() == 9) {
return std::string{s[6], s[3], s[0], s[7], s[4], s[1], s[8], s[5], s[2]};
}
abort();
}
[[nodiscard]] auto flip(std::string const& s) -> std::string
{
if (s.size() == 4) {
return s.substr(2) + s.substr(0, 2);
}
if (s.size() == 9) {
return s.substr(6) + s.substr(3, 3) + s.substr(0, 3);
}
abort();
}
struct Patterns
{
void add(std::string const& s1, std::string const& s2, std::string const& target)
{
auto s{s1 + s2};
for (auto j{0}; j < 2; ++j) {
for (auto i{0}; i < 4; ++i) {
map_.insert({s, target});
s = rotate(s);
}
s = flip(s);
}
}
void add(std::string const& s1, std::string const& s2, std::string const& s3,
std::string const& target)
{
auto s{s1 + s2 + s3};
for (auto j{0}; j < 2; ++j) {
for (auto i{0}; i < 4; ++i) {
map_.insert({s, target});
s = rotate(s);
}
s = flip(s);
}
}
std::string const& find(std::string const& s)
{
static std::string empty;
auto it{map_.find(s)};
if (it == map_.end()) {
return empty;
}
return it->second;
}
std::map<std::string, std::string> map_;
};
auto main() -> int
{
static std::regex re2{"([.#][.#])/([.#][.#]) => ([.#][.#][.#])/([.#][.#][.#])/([.#][.#][.#])"};
static std::regex re3{
"([.#][.#][.#])/([.#][.#][.#])/([.#][.#][.#]) => "
"([.#][.#][.#][.#])/([.#][.#][.#][.#])/([.#][.#][.#][.#])/([.#][.#][.#][.#])"};
Patterns patterns;
std::string line;
while (std::getline(std::cin, line) && !line.empty()) {
std::smatch m;
if (std::regex_search(line, m, re2)) {
patterns.add(m.str(1), m.str(2), m.str(3) + m.str(4) + m.str(5));
}
else if (std::regex_search(line, m, re3)) {
patterns.add(m.str(1), m.str(2), m.str(3), m.str(4) + m.str(5) + m.str(6) + m.str(7));
}
else {
std::cerr << "Unable to interpret:" << line << '\n';
return 1;
}
}
std::string grid{".#...####"};
unsigned width{3};
for (unsigned i{0}; i < 5; ++i) {
assert(grid.size() == width * width);
std::string new_grid;
if (width % 2 == 0) {
for (unsigned y{0}; y < grid.size(); y += width * 2) {
std::string l1;
std::string l2;
std::string l3;
for (unsigned x{0}; x < width; x += 2) {
auto pattern{grid.substr(y + x, 2) + grid.substr(y + width + x, 2)};
auto expand{patterns.find(pattern)};
assert(!expand.empty());
l1 += expand.substr(0, 3);
l2 += expand.substr(3, 3);
l3 += expand.substr(6);
}
new_grid += l1 + l2 + l3;
}
width = (width / 2) * 3;
}
else {
assert(width % 3 == 0);
for (unsigned y{0}; y < grid.size(); y += width * 3) {
std::string l1;
std::string l2;
std::string l3;
std::string l4;
for (unsigned x{0}; x < width; x += 3) {
auto pattern{grid.substr(y + x, 3) + grid.substr(y + width + x, 3) +
grid.substr(y + width * 2 + x, 3)};
auto expand{patterns.find(pattern)};
assert(!expand.empty());
l1 += expand.substr(0, 4);
l2 += expand.substr(4, 4);
l3 += expand.substr(8, 4);
l4 += expand.substr(12);
}
new_grid += l1 + l2 + l3 + l4;
}
width = (width / 3) * 4;
}
std::swap(grid, new_grid);
}
std::cout << "Number of lit cells: " << std::count(grid.begin(), grid.end(), '#') << '\n';
return 0;
}

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#include <cassert>
#include <iostream>
#include <map>
#include <regex>
#include <string>
[[nodiscard]] auto rotate(std::string const& s) -> std::string
{
if (s.size() == 4) {
return std::string{s[2], s[0], s[3], s[1]};
}
if (s.size() == 9) {
return std::string{s[6], s[3], s[0], s[7], s[4], s[1], s[8], s[5], s[2]};
}
abort();
}
[[nodiscard]] auto flip(std::string const& s) -> std::string
{
if (s.size() == 4) {
return s.substr(2) + s.substr(0, 2);
}
if (s.size() == 9) {
return s.substr(6) + s.substr(3, 3) + s.substr(0, 3);
}
abort();
}
struct Patterns
{
void add(std::string const& s1, std::string const& s2, std::string const& target)
{
auto s{s1 + s2};
for (auto j{0}; j < 2; ++j) {
for (auto i{0}; i < 4; ++i) {
map_.insert({s, target});
s = rotate(s);
}
s = flip(s);
}
}
void add(std::string const& s1, std::string const& s2, std::string const& s3,
std::string const& target)
{
auto s{s1 + s2 + s3};
for (auto j{0}; j < 2; ++j) {
for (auto i{0}; i < 4; ++i) {
map_.insert({s, target});
s = rotate(s);
}
s = flip(s);
}
}
std::string const& find(std::string const& s)
{
static std::string empty;
auto it{map_.find(s)};
if (it == map_.end()) {
return empty;
}
return it->second;
}
std::map<std::string, std::string> map_;
};
auto main() -> int
{
static std::regex re2{"([.#][.#])/([.#][.#]) => ([.#][.#][.#])/([.#][.#][.#])/([.#][.#][.#])"};
static std::regex re3{
"([.#][.#][.#])/([.#][.#][.#])/([.#][.#][.#]) => "
"([.#][.#][.#][.#])/([.#][.#][.#][.#])/([.#][.#][.#][.#])/([.#][.#][.#][.#])"};
Patterns patterns;
std::string line;
while (std::getline(std::cin, line) && !line.empty()) {
std::smatch m;
if (std::regex_search(line, m, re2)) {
patterns.add(m.str(1), m.str(2), m.str(3) + m.str(4) + m.str(5));
}
else if (std::regex_search(line, m, re3)) {
patterns.add(m.str(1), m.str(2), m.str(3), m.str(4) + m.str(5) + m.str(6) + m.str(7));
}
else {
std::cerr << "Unable to interpret:" << line << '\n';
return 1;
}
}
std::string grid{".#...####"};
unsigned width{3};
for (unsigned i{0}; i < 18; ++i) {
assert(grid.size() == width * width);
std::string new_grid;
if (width % 2 == 0) {
for (unsigned y{0}; y < grid.size(); y += width * 2) {
std::string l1;
std::string l2;
std::string l3;
for (unsigned x{0}; x < width; x += 2) {
auto pattern{grid.substr(y + x, 2) + grid.substr(y + width + x, 2)};
auto expand{patterns.find(pattern)};
assert(!expand.empty());
l1 += expand.substr(0, 3);
l2 += expand.substr(3, 3);
l3 += expand.substr(6);
}
new_grid += l1 + l2 + l3;
}
width = (width / 2) * 3;
}
else {
assert(width % 3 == 0);
for (unsigned y{0}; y < grid.size(); y += width * 3) {
std::string l1;
std::string l2;
std::string l3;
std::string l4;
for (unsigned x{0}; x < width; x += 3) {
auto pattern{grid.substr(y + x, 3) + grid.substr(y + width + x, 3) +
grid.substr(y + width * 2 + x, 3)};
auto expand{patterns.find(pattern)};
assert(!expand.empty());
l1 += expand.substr(0, 4);
l2 += expand.substr(4, 4);
l3 += expand.substr(8, 4);
l4 += expand.substr(12);
}
new_grid += l1 + l2 + l3 + l4;
}
width = (width / 3) * 4;
}
std::swap(grid, new_grid);
}
std::cout << "Number of lit cells: " << std::count(grid.begin(), grid.end(), '#') << '\n';
return 0;
}