Files
advent-of-code/2020/day_5/binary_boarding.cc
2020-12-06 03:31:53 -03:00

46 lines
1.1 KiB
C++

#include <algorithm>
#include <vector>
#include <set>
#include <string>
#include <fstream>
#include <iostream>
std::vector<std::string> read_input_file() {
std::ifstream file("input");
std::vector<std::string> data;
std::string line;
while(std::getline(file, line)) data.push_back(line);
return data;
}
template <typename T>
T peek_back(T it) {
return --it;
}
int parse_id(std::string ticket) {
std::replace(ticket.begin(), ticket.end(), 'F', '0');
std::replace(ticket.begin(), ticket.end(), 'L', '0');
std::replace(ticket.begin(), ticket.end(), 'B', '1');
std::replace(ticket.begin(), ticket.end(), 'R', '1');
return stoi(ticket, nullptr, 2);
}
int solve_a(const std::set<int> &ids) { return *ids.rbegin(); }
int solve_b(const std::set<int> &ids) {
for(auto it = ++ids.begin(); it != ids.end(); it++){
if(*peek_back(it) + 2 == *it) return *it - 1;
}
return 0;
}
int main() {
std::set<int> ids;
for(auto &ticket: read_input_file()) ids.insert(parse_id(ticket));
std::cout << solve_a(ids) << " " << solve_b(ids) << std::endl;
}