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#include <fstream>
#include <iostream>
#include <sstream>
#include <string>
#include <tuple>
#include <vector>
using namespace std;
vector<tuple<long, vector<long>>>
read_file(string_view filename)
{
fstream input{ filename };
vector<tuple<long, vector<long>>> data;
for ( string line; getline(input, line); ) {
auto pos = line.find(':');
stringstream str{ line.substr(pos + 1) };
data.emplace_back(stol(line.substr(0, pos)), vector<long>{ istream_iterator<long>{ str }, {} });
}
return data;
}
bool
can_evaluated(long first, const vector<long>& values)
{
for ( unsigned long pattern = 0; pattern != (1U << (values.size() - 1)); ++pattern ) {
long result = values.at(0);
for ( size_t idx = 1; idx < values.size(); ++idx ) {
if ( (pattern & (1U << (idx - 1))) == 0 ) {
result += values.at(idx);
}
else {
result *= values.at(idx);
}
}
if ( first == result ) {
return true;
}
}
return false;
}
void
part1(const vector<tuple<long, vector<long>>>& data)
{
long sum = 0;
for ( const auto& [first, values]: data ) {
if ( can_evaluated(first, values) ) {
sum += first;
}
}
cout << sum << endl;
}
size_t
ipow(size_t base, size_t exp) // NOLINT
{
size_t result = 1;
while ( exp != 0 ) {
if ( (exp & 1U) == 1 ) {
result *= base;
}
exp >>= 1U;
base *= base;
}
return result;
}
bool
can_evaluated2(long first, const vector<long>& values)
{
const auto N = ipow(3, values.size() - 1); // NOLINT
for ( unsigned long pattern = 0; pattern != N; ++pattern ) {
auto test_pattern = pattern;
long result = values.at(0);
for ( size_t idx = 1; idx < values.size(); ++idx ) {
auto rem = test_pattern % 3;
if ( rem == 0 ) {
result += values.at(idx);
}
else if ( rem == 1 ) {
result *= values.at(idx);
}
else {
result = stol(to_string(result) + to_string(values.at(idx)));
}
test_pattern /= 3;
}
if ( first == result ) {
return true;
}
}
return false;
}
void
part2(const vector<tuple<long, vector<long>>>& data)
{
long sum = 0;
for ( const auto& [first, values]: data ) {
if ( can_evaluated2(first, values) ) {
sum += first;
}
}
cout << sum << endl;
}
int
main()
{
auto data = read_file("data/day07.txt");
part1(data);
part2(data);
}
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