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#include <fstream>
#include <iostream>
#include <string>
#include <tuple>
#include <vector>
using namespace std;
enum Instruction {
Half_A,
Half_B,
Triple_A,
Triple_B,
Inc_A,
Inc_B,
Jmp,
Jmp_Even_A,
Jmp_Even_B,
Jmp_One_A,
Jmp_One_B
};
vector<tuple<Instruction, int>>
read_file(string_view filename)
{
fstream input{ filename };
vector<tuple<Instruction, int>> instructions;
for ( string line; getline(input, line); ) {
if ( line == "hlf a" ) {
instructions.emplace_back(Half_A, 0);
}
else if ( line == "hlf b" ) {
instructions.emplace_back(Half_B, 0);
}
else if ( line == "tpl a" ) {
instructions.emplace_back(Triple_A, 0);
}
else if ( line == "tpl b" ) {
instructions.emplace_back(Triple_B, 0);
}
else if ( line == "inc a" ) {
instructions.emplace_back(Inc_A, 0);
}
else if ( line == "inc b" ) {
instructions.emplace_back(Inc_B, 0);
}
else if ( line.starts_with("jmp ") ) {
auto offset = stoi(line.substr(4));
instructions.emplace_back(Jmp, offset);
}
else if ( line.starts_with("jie a, ") ) {
auto offset = stoi(line.substr(7));
instructions.emplace_back(Jmp_Even_A, offset);
}
else if ( line.starts_with("jie b, ") ) {
auto offset = stoi(line.substr(7));
instructions.emplace_back(Jmp_Even_B, offset);
}
else if ( line.starts_with("jio a, ") ) {
auto offset = stoi(line.substr(7));
instructions.emplace_back(Jmp_One_A, offset);
}
else if ( line.starts_with("jio b, ") ) {
auto offset = stoi(line.substr(7));
instructions.emplace_back(Jmp_One_B, offset);
}
else {
cerr << "unknown instruction: " << line << endl;
}
}
return instructions;
}
int
eval(const vector<tuple<Instruction, int>>& instructions, int a, int b)
{
for ( size_t ip = 0; ip < instructions.size(); ) {
const auto [instruction, offset] = instructions[ip++];
switch ( instruction ) {
case Half_A:
a /= 2;
break;
case Half_B:
b /= 2;
break;
case Triple_A:
a *= 3;
break;
case Triple_B:
b *= 3;
break;
case Inc_A:
a++;
break;
case Inc_B:
b++;
break;
case Jmp:
ip = (ip - 1) + size_t(offset);
break;
case Jmp_Even_A:
if ( a % 2 == 0 ) {
ip = (ip - 1) + size_t(offset);
}
break;
case Jmp_Even_B:
if ( b % 2 == 0 ) {
ip = (ip - 1) + size_t(offset);
}
break;
case Jmp_One_A:
if ( a == 1 ) {
ip = (ip - 1) + size_t(offset);
}
break;
case Jmp_One_B:
if ( b == 1 ) {
ip = (ip - 1) + size_t(offset);
}
break;
}
}
return b;
}
void
part1(const vector<tuple<Instruction, int>>& instructions)
{
cout << eval(instructions, 0, 0) << endl;
}
void
part2(const vector<tuple<Instruction, int>>& instructions)
{
cout << eval(instructions, 1, 0) << endl;
}
int
main()
{
auto instructions = read_file("data/day23.txt");
part1(instructions);
part2(instructions);
}
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