Files
AdventOfCode/2025/day2.hpp
2025-12-02 11:44:29 +00:00

117 lines
3.1 KiB
C++

#include "aoc.hpp"
#include <algorithm>
#include <unordered_map>
class Day02 : public AOCDay
{
public:
Day02() {}
~Day02() {}
int Day() override {return 2;}
int PartOne(File& f) override
{
f.SplitBy(",");
uint64_t res = 0;
// Range of ID's (11-22)
for (auto range : f.TokensForLine(0))
{
int dash = range.Data.find('-', 0);
uint64_t a = std::stoll(range.Data.substr(0, dash));
uint64_t b = std::stoll(range.Data.substr(dash + 1));
for (uint64_t i = a; i <= b; i++)
{
// Convert number back into string
std::string current = std::to_string(i);
// import 'is-odd' lol
if (current.length() & 1) continue;
int mid = current.length() / 2;
uint64_t l = std::stoll(current.substr(0, mid));
uint64_t r = std::stoll(current.substr(mid));
if (l == r)
{
res += i;
}
}
}
std::cout << "The answer doesn't fit in int : "<< res << std::endl;
return res;
}
int PartTwo(File& f) override
{
f.SplitBy(",");
uint64_t res = 0;
for (auto range : f.TokensForLine(0))
{
int dash = range.Data.find('-', 0);
uint64_t a = std::stoll(range.Data.substr(0, dash));
uint64_t b = std::stoll(range.Data.substr(dash + 1));
for (uint64_t i = a; i <= b; i++)
{
std::string current = std::to_string(i);
int n = current.length();
bool invalid = false;
// Try every possible substring start (i)
for (int start = 0; start < n && !invalid; start++)
{
std::string accum;
// Build accum char-by-char
for (int end = start; end < n && !invalid; end++)
{
accum.push_back(current[end]);
int len = accum.length();
int remaining = n - start;
// Now check if repeats match
bool matches = true;
for (int rep = 0; rep < remaining / len; rep++)
{
if (current.compare(start + rep * len, len, accum) != 0)
{
matches = false;
break;
}
}
// Must be at least two repeats
if (matches && remaining / len >= 2)
{
invalid = true;
break;
}
}
}
if (invalid)
res += i;
}
}
std::cout << "The answer doesn't fit in int : "<< res << std::endl;
return res;
}
};
ADD_AOC_DAY(Day02);