AOC 2024 Problem 5 Part 1 N^2 * M Complexity? No problem for C++!

aoc-2024-5-1.cpp

#include <iostream>
#include <fstream>
#include <string>
#include <ctype.h>
#include <vector>
#include <algorithm>
#include <unordered_map>
#include <sstream>
#include <regex>
#include <utility>

using namespace std;

// Complexity of N^2 * M ? No problem for C++!
bool checkForValidity(std::vector<std::pair<int, int>> rules, std::vector<int> pages)
{
    // check all pairs of pages
    for (int i = 0; i < pages.size(); i++) {
        for (int j = i + 1; j < pages.size(); j++) {
            int a = pages[i];
            int b = pages[j];

            for (int k = 0; k < rules.size(); k++) {
                auto rule = rules[k];
                if (rule.first == b && rule.second == a) {
                    return false;
                }
            }
        }
    }
    return true;
}

int main()
{
    ifstream infile("input.txt");

    if (!infile.is_open()) {
        cout << "File prob\n";
        return -1;
    }
    string line;
    std::vector<std::pair<int, int>> rules;
    while (infile.good()) {
        getline(infile, line);
        if (line.empty()) break;
        int x, y;
        auto pos = line.find('|');
        std::string firstNumS = line.substr(0, pos);
        std::string secondNumS = line.substr(pos + 1);
        int page1 = std::stoi(firstNumS);
        int page2 = std::stoi(secondNumS);
        rules.emplace_back(page1, page2);
    }

    int total = 0;
    while (infile.good()) {
        getline(infile, line);
        if (line.empty()) break;
        std::vector<int> pages;
        
        char separator = ',';
        int offset = 0;
        int pos;
        do {
            pos = line.find(separator, offset);
            std::string str = line.substr(offset, pos - offset);
            pages.push_back(std::stoi(str));
            offset = pos + 1;
        } while (pos != std::string::npos);
        auto isvalid = checkForValidity(rules, pages);
        
        if (isvalid) {
            int mid = pages[pages.size() / 2];
            total += mid;
        }
    }

    std::cout << total << std::endl;
}