day two

2nd_day/2/main.cpp

@@ -0,0 +1,73 @@
+#include <fstream>
+#include <iostream>
+#include <set>
+#include <string>
+#include <vector>
+
+using namespace std;
+
+vector<string> get_input_from_file(const string file_name) {
+  ifstream file(file_name);
+  string input;
+  getline(file, input);
+  input += ",";
+
+  size_t pos;
+  vector<string> ids;
+
+  while ((pos = input.find(",")) != string::npos) {
+    if (pos == 0) {
+      input.erase(0, 1);
+      continue;
+    }
+    string id = input.substr(0, pos);
+    ids.push_back(id);
+    input.erase(0, pos + 1);
+  }
+
+  file.close();
+
+  return ids;
+}
+
+bool is_id_periodic(string id) {
+  if (id.size() < 2)
+    return false;
+  return (id + id).find(id, 1) < id.size();
+}
+
+vector<string> get_invalid_ids(const string range) {
+  const size_t delimeter_pos = range.find("-");
+  const int length = range.length();
+
+  const long long start = stoll(range.substr(0, delimeter_pos));
+  const long long end = stoll(range.substr(delimeter_pos + 1));
+
+  vector<string> periodic_ids;
+
+  for (long long id = start; id <= end; id++) {
+    if (is_id_periodic(to_string(id))) {
+      periodic_ids.push_back(to_string(id));
+    }
+  }
+  return periodic_ids;
+}
+
+int main() {
+  const string FILE_NAME = "input.txt";
+  vector<string> ids = get_input_from_file(FILE_NAME);
+
+  set<string> all_periodc_ids;
+
+  for (string id : ids) {
+    vector<string> invalid = get_invalid_ids(id);
+    all_periodc_ids.insert(invalid.begin(), invalid.end());
+  }
+
+  long long sum = 0;
+  for (string id : all_periodc_ids) {
+    sum += stoll(id);
+  }
+
+  cout << "Sum of invalid ids: " << sum << endl;
+}