#include #include #include using namespace std; vector> readInput() { vector> list; string line; while (getline(cin, line)) { list.push_back({}); stringstream stream(line); int value; while (stream >> value) { list.back().push_back(value); } } return list; } int getIndexOfUnsafeValue(const vector &report) { const int MAX_SAFE_DIFFERENCE = 3; int directionOfChange = (report.front() < report.back()) ? 1 : -1; for (size_t i = 0; i < report.size() - 1; i++) { int levelDifference = (report[i + 1] - report[i]) * directionOfChange; if (levelDifference <= 0 || levelDifference > MAX_SAFE_DIFFERENCE) { return i; } } return -1; } bool isSafeReport(const vector &report, const bool applyDampener) { int indexOfUnsafeValue = getIndexOfUnsafeValue(report); if (indexOfUnsafeValue == -1) { return true; } if (!applyDampener) { return false; } vector tempReport = report; int unsafeValue = report[indexOfUnsafeValue]; tempReport.erase(tempReport.begin() + indexOfUnsafeValue); if (getIndexOfUnsafeValue(tempReport) == -1) { return true; } tempReport.insert(tempReport.begin() + indexOfUnsafeValue, unsafeValue); tempReport.erase(tempReport.begin() + indexOfUnsafeValue + 1); return getIndexOfUnsafeValue(tempReport) == -1; } int calculateNumberOfSafeReports(const vector> &list, const bool applyDampener) { int numberOfSafeReports = 0; for (const vector &report : list) { numberOfSafeReports += isSafeReport(report, applyDampener); } return numberOfSafeReports; } int main() { vector> list = readInput(); // Part one cout << "Number of safe reports: " << calculateNumberOfSafeReports(list, false) << endl; // Part two cout << "Number of safe reports (when taking the dampener into account): " << calculateNumberOfSafeReports(list, true) << endl; }