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advent-of-code/2016/puzzle-07-01.cc

41 lines
929 B
C++

//
// Created by Matthew Gretton-Dann on 04/12/2021.
//
#include <array>
#include <iostream>
#include <string>
auto abba(std::string const& line)
{
enum State { outside, inside };
std::array<bool, 2> seen{false, false};
State state{State::outside};
for (std::size_t idx{0}; idx < line.size() - 3; ++idx) {
if (line[idx] == '[') {
state = State::inside;
}
else if (line[idx] == ']') {
state = State::outside;
}
else if (line[idx] != line[idx + 1] && line[idx + 1] == line[idx + 2] &&
line[idx] == line[idx + 3]) {
seen[static_cast<unsigned>(state)] = true;
}
}
return seen[State::outside] && !seen[State::inside];
}
auto main() -> int
{
std::string line;
unsigned good_count{0};
while (std::getline(std::cin, line)) {
if (abba(line)) {
++good_count;
}
}
std::cout << "ABBA lines that support TLS: " << good_count << '\n';
return 0;
}