Reimar/adventofcode-2025
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Solve day 2 part 2

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Reimar 2025-12-17 09:53:53 +01:00
parent aa911a88fb
commit 1a1e6c18f0
1 changed files with 25 additions and 10 deletions
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35
day_2.cpp
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@ -1,10 +1,10 @@
#include <fstream> #include <fstream>
#include <iostream> #include <iostream>
bool is_invalid(long int id) bool is_invalid_part_1(long int id)
{ {
std::string id_str = std::to_string(id); std::string id_str = std::to_string(id);
for (int i = 0; i < id_str.size(); i++) { for (int i = 1; i < id_str.size(); i++) {
if (id_str.substr(0, i) + id_str.substr(0, i) == id_str) { if (id_str.substr(0, i) + id_str.substr(0, i) == id_str) {
return true; return true;
} }
@ -12,26 +12,41 @@ bool is_invalid(long int id)
return false; return false;
} }
bool is_invalid_part_2(long int id)
{
std::string id_str = std::to_string(id);
for (int repeat_length = 1; repeat_length < id_str.size(); repeat_length++) {
for (int repeat_count = 0; repeat_count < id_str.size() / repeat_length + 1; repeat_count++) {
std::string new_str;
for (int i = 0; i < repeat_count; i++) {
new_str += id_str.substr(0, repeat_length);
}
if (new_str == id_str) return true;
}
}
return false;
}
int main() int main()
{ {
std::ifstream file("input.txt"); std::ifstream file("input.txt");
long int invalid_sum = 0; long int part_1_invalid_sum = 0, part_2_invalid_sum = 0;
std::string range; std::string range;
while (getline(file, range, ',')) { while (getline(file, range, ',')) {
long int range_start, range_end; long int range_start, range_end;
sscanf(range.c_str(), "%ld-%ld", &range_start, &range_end); sscanf(range.c_str(), "%ld-%ld", &range_start, &range_end);
std::cout << "Range " << range_start << "-" << range_end << ":"; std::cout << "Range " << range_start << "-" << range_end << std::endl;
for (long int i = range_start; i <= range_end; i++) { for (long int i = range_start; i <= range_end; i++) {
if (is_invalid(i)) { if (is_invalid_part_1(i)) part_1_invalid_sum += i;
std::cout << " " << i; if (is_invalid_part_2(i)) part_2_invalid_sum += i;
invalid_sum += i;
}
} }
std::cout << std::endl;
} }
std::cout << "Sum of invalid IDs: " << invalid_sum << std::endl; std::cout << std::endl;
std::cout << "Sum of invalid IDs:\n Part 1: " << part_1_invalid_sum << "\n Part 2: " << part_2_invalid_sum << std::endl;
} }