AdventOfCode2024/Aufgabe 2/main.cpp

#include <iostream>
#include <vector>
#include <fstream>

std::vector<std::string> readTextFromFile(const std::string& fileName) {
    std::vector<std::string> lines;
    std::ifstream file(fileName);
    if (!file) {  // Überprüft, ob die Datei geöffnet werden konnte
        std::cerr << "Fehler: Datei konnte nicht geöffnet werden: " << fileName << std::endl;
        return lines;
    }
    std::string s;
    while(getline(file, s)) {
        lines.push_back(s);
    }
    return lines;
}

std::vector<std::string> splitString(const std::string& input, char ch) {
    std::vector<std::string> splittedString;
    size_t pos = input.find(ch);
    size_t initialPos = 0;

    while(pos != std::string::npos) {
        splittedString.push_back(input.substr(initialPos, pos - initialPos));
        initialPos = pos + 1;
        pos = input.find(ch, initialPos);
    }

    splittedString.push_back(input.substr(initialPos, std::min(pos, input.size()) - initialPos));

    return splittedString;
}

std::vector<int> convertReportToNumericalReport(const std::vector<std::string>& splittedReport) {
    std::vector<int> numericalReport;
    for(const auto& s : splittedReport) {
        numericalReport.push_back(std::stoi(s));
    }
    return numericalReport;
}

bool isReportSave(std::vector<int>& numericalReport) {
    bool isIncreasing = true;
    bool isDecreasing = true;

    for(int i=0; i<numericalReport.size()-1; i++) {
        if(numericalReport.at(i) > numericalReport.at(i+1)) {
            isDecreasing = false;
        }

        if(numericalReport.at(i) < numericalReport.at(i+1)) {
            isIncreasing = false;
        }

        int differ = std::abs(numericalReport.at(i) - numericalReport.at(i+1));
        if(differ < 1 || differ > 3) {
            return false;
        }
    }

    return isIncreasing || isDecreasing;
}

bool isReportSaveTolerateBadLevel(std::vector<int>& numericalReport) {
    //First: Check if report is already counted as save
    if(isReportSave(numericalReport))  return true;

    //Check if a single level can be removed such that the report counts as safe
    for(int i=0; i < numericalReport.size(); i++) {
        int potentialBadLevel = numericalReport.at(i);
        numericalReport.erase(numericalReport.begin() + i);
        if(isReportSave(numericalReport)) {
            return true;
        } else {
            numericalReport.insert(numericalReport.begin() + i, potentialBadLevel);
        }
    }
    return false;
}


int calcNumberSaveReports(std::vector<std::string> reports) {
    int saveReports = 0;
    for(const auto& report : reports) {
        std::vector<std::string> splittedReport = splitString(report, ' ');
        std::vector<int> numericalReport = convertReportToNumericalReport(splittedReport);
        if(isReportSave(numericalReport)) {
            saveReports++;
        }
    }
    return saveReports;
}

int calcNumberSaveReportsTolerateBadLevel(std::vector<std::string> reports) {
    int saveReports = 0;
    for(const auto& report : reports) {
        std::vector<std::string> splittedReport = splitString(report, ' ');
        std::vector<int> numericalReport = convertReportToNumericalReport(splittedReport);
        if(isReportSaveTolerateBadLevel(numericalReport)) {
            saveReports++;
        }
    }
    return saveReports;
}

int main() {
    std::string inputFile = "../input.txt";
    std::vector<std::string> reports = readTextFromFile(inputFile);

    int result = calcNumberSaveReports(reports);
    std::cout << "There are " << result << " save reports" << std::endl;

    int resultBadLevel = calcNumberSaveReportsTolerateBadLevel(reports);
    std::cout << "There are " << resultBadLevel << " save reports when tolerating single bad levels!" << std::endl;
    return 0;
}