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2023 Day 12 Part 2 Proposed soln

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Not scanning the whole string everytime.
This commit is contained in:
Matthew Gretton-Dann
2023-12-12 10:30:09 +00:00
parent 0febe907d1
commit 3ca1d02fab
1 changed files with 7 additions and 9 deletions
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16
2023/puzzle-12-02.cc
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@@ -62,17 +62,16 @@ auto split(std::string_view line) -> std::pair<std::string_view, UIntVec>
void generate_pattern(std::string start, UIntVec::const_iterator it, UIntVec::const_iterator end, void generate_pattern(std::string start, UIntVec::const_iterator it, UIntVec::const_iterator end,
std::string_view pattern, UInt hash_count, UInt& count) std::string_view pattern, UInt hash_count, UInt& count)
{ {
for (std::size_t p{0}; p + start.size() < pattern.size() && p < *it; ++p) { auto pos = start.size();
if (pattern[start.size() + p] == '.') { return; } auto num_hashs = *it++;
} start += std::string(num_hashs, '#');
start += std::string(*it++, '#');
if (it == end) { if (it == end) {
if (start.size() <= pattern.size()) { if (start.size() <= pattern.size()) {
start.resize(pattern.size(), '.'); start.resize(pattern.size(), '.');
if (validate_subpattern(pattern, start, hash_count, end - it - 1)) { if (validate_subpattern(pattern.substr(pos), start.substr(pos), num_hashs, 0)) {
++count; ++count;
if (count % 100'000 == 0) { if (count % 1'000'000 == 0) {
std::cout << start << '\n'; std::cout << start << '\n';
} }
} }
@@ -81,8 +80,8 @@ void generate_pattern(std::string start, UIntVec::const_iterator it, UIntVec::co
} }
start += '.'; start += '.';
while (validate_subpattern(pattern, start, hash_count, end - it - 1)) { while (validate_subpattern(pattern.substr(pos), start.substr(pos), hash_count, end - it - 1)) {
generate_pattern(start, it, end, pattern, hash_count, count); generate_pattern(start, it, end, pattern, hash_count - num_hashs, count);
start += '.'; start += '.';
} }
} }
@@ -94,7 +93,6 @@ auto valid_sequences(std::string_view pattern, UIntVec const& nums) -> UInt
for (auto num : nums) { hash_count += num; } for (auto num : nums) { hash_count += num; }
std::string start; std::string start;
while (validate_subpattern(pattern, start, hash_count, nums.size() - 1)) { while (validate_subpattern(pattern, start, hash_count, nums.size() - 1)) {
std::cout << start << '\n';
generate_pattern(start, nums.begin(), nums.end(), pattern, hash_count, count); generate_pattern(start, nums.begin(), nums.end(), pattern, hash_count, count);
start += '.'; start += '.';
} }