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#include <fstream>
#include <iostream>
#include <map>
#include <stack>
#include <string>
#include <tuple>
#include <vector>
using namespace std;
using instructions_t = vector<tuple<size_t, size_t, size_t>>;
using stacks_t = map<size_t, stack<char>>;
void
read_file(string_view filename, instructions_t& instructions, stacks_t& stacks)
{
fstream input{ filename };
vector<string> lines;
instructions.clear();
for ( string line; getline(input, line); ) {
if ( line.length() == 0 ) {
continue;
}
else if ( line.starts_with("move") ) {
size_t a, b, c;
sscanf(line.c_str(), "move %zu from %zu to %zu", &a, &b, &c);
instructions.emplace_back(a, b, c);
}
else if ( line.find('[') != string::npos ) {
lines.emplace_back(line);
}
}
reverse(begin(lines), end(lines));
stacks.clear();
for ( const auto& line: lines ) {
for ( size_t col = 0; col * 4 < line.length(); ++col ) {
auto chr = line[col * 4 + 1];
if ( isalpha(chr) != 0 ) {
stacks[col + 1].push(chr);
}
}
}
}
void
part1(const instructions_t& instructions, stacks_t stacks)
{
for ( const auto& [amount, from, to]: instructions ) {
for ( size_t i = 0; i != amount; ++i ) {
const auto value = stacks[from].top();
stacks[from].pop();
stacks[to].emplace(value);
}
}
for ( size_t i = 0; i != stacks.size(); ++i ) {
cout << stacks[i + 1].top();
}
cout << endl;
}
void
part2(const instructions_t& instructions, stacks_t stacks)
{
for ( const auto& [amount, from, to]: instructions ) {
vector<char> values;
for ( size_t i = 0; i != amount; ++i ) {
const auto value = stacks[from].top();
stacks[from].pop();
values.emplace_back(value);
}
reverse(begin(values), end(values));
for ( const auto& value: values ) {
stacks[to].emplace(value);
}
}
for ( size_t i = 0; i != stacks.size(); ++i ) {
cout << stacks[i + 1].top();
}
cout << endl;
}
int
main()
{
instructions_t instructions;
stacks_t stacks;
read_file("data/day05.txt", instructions, stacks);
part1(instructions, stacks);
part2(instructions, stacks);
}
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