AOC 2024 Problem 2 Part 2

aoc2024-2-2.cpp

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

using namespace std;

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

  if (!infile.is_open()) {
    cout << "File prob\n";
    return -1;
  }
  int safeReportsCount = 0;
  string line;
  while (infile.good()) {
    getline(infile, line);

    if (line.empty()) continue;
    std::vector<int> report;

    std::stringstream ss(line);

    while (!ss.eof()) {
      int n;
      ss >> n;
      report.push_back(n);
    }


    for (int skipIdx = 0; skipIdx < report.size(); skipIdx++) {
      std::vector<int> reportWithoutOne = report;

      reportWithoutOne.erase(reportWithoutOne.begin() + skipIdx);

      std::string newline;

      for (int i = 0; i < reportWithoutOne.size(); i++) {
        newline += std::to_string(reportWithoutOne[i]);
        if (i != reportWithoutOne.size() - 1) {
          newline += ' ';
        }
      }

      std::stringstream ss(newline);
      bool isSafe = true;
      int prev;
      int n;
      ss >> prev >> n;
      int diff = abs(prev - n);
      bool incr = n - prev > 0;
      prev = n;
      if (diff < 1 || diff > 3) {
        isSafe = false;
      }
      while (!ss.eof() && isSafe) {
        ss >> n;
        bool isIncr = n - prev > 0;
        diff = abs(prev - n);
        if (isIncr != incr || diff < 1 || diff > 3) {
          isSafe = false;
          break;
        }
        prev = n;
      }

      if (isSafe) {
        safeReportsCount++;
        break;
      }
    }
  }
  infile.close();

  std::cout << safeReportsCount << std::endl;
}