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#include <fstream>
#include <iostream>
#include <map>
#include <string>
#include <tuple>
#include <vector>
using namespace std;
vector<string>
read_file(string_view filename)
{
fstream input{ filename };
vector<string> lines;
for ( string line; getline(input, line); ) {
lines.emplace_back(line);
}
return lines;
}
void
part1(const vector<string>& lines)
{
int pos_x = 1;
int pos_y = 1;
for ( const auto& line: lines ) {
for ( const auto chr: line ) {
switch ( chr ) {
case 'U':
--pos_y;
break;
case 'R':
++pos_x;
break;
case 'L':
--pos_x;
break;
case 'D':
++pos_y;
break;
default:
cerr << "unknown char: " << chr << endl;
return;
}
pos_x = clamp(pos_x, 0, 2);
pos_y = clamp(pos_y, 0, 2);
}
cout << pos_y * 3 + pos_x + 1;
}
cout << endl;
}
void
part2(const vector<string>& lines)
{
const map<tuple<int, int>, char> keypad = {
{ { 2, 0 }, '1' },
{ { 1, 1 }, '2' },
{ { 2, 1 }, '3' },
{ { 3, 1 }, '4' },
{ { 0, 2 }, '5' },
{ { 1, 2 }, '6' },
{ { 2, 2 }, '7' },
{ { 3, 2 }, '8' },
{ { 4, 2 }, '9' },
{ { 1, 3 }, 'A' },
{ { 2, 3 }, 'B' },
{ { 3, 3 }, 'C' },
{ { 2, 4 }, 'D' }
};
tuple<int, int> pos = { 0, 2 };
for ( const auto& line: lines ) {
for ( const auto chr: line ) {
auto pos2 = pos;
switch ( chr ) {
case 'U':
--get<1>(pos2);
break;
case 'R':
++get<0>(pos2);
break;
case 'L':
--get<0>(pos2);
break;
case 'D':
++get<1>(pos2);
break;
default:
cerr << "unknown char: " << chr << endl;
return;
}
if ( keypad.contains(pos2) ) {
pos = pos2;
}
}
cout << keypad.at(pos);
}
cout << endl;
}
int
main()
{
auto lines = read_file("data/day02.txt");
part1(lines);
part2(lines);
}
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