Advent Of Code - Day 1

day1.cpp

#include <iostream>
#include <fstream>
#include <string>
#include <ctype.h>
#include <math.h>

using namespace std;

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

    if (!infile.is_open()) {
        cout << "File prob\n"; return -1;
    }

    string line;
    unsigned long long sum = 0;
    string nums[10]{ "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };

    while (infile.good()) {
        getline(infile, line);
        int idxs[10]{ -1,-1,-1,-1,-1,-1,-1,-1 };
        int maxidxs[10] = { -1,-1,-1,-1,-1,-1,-1,-1 };
        long long minIdx = 99999999, firstN = 0, lastN = 0, maxIdx = -1;

        // Find the index of first and last digit or 'digit word'
        for (size_t i = 0; i < 10; i++) {
            idxs[i] = min(line.find(nums[i], 0), line.find(to_string(i), 0));
            maxidxs[i] = max(static_cast<int>(line.rfind(nums[i])), static_cast<int>(line.rfind(to_string(i))));
        }

        // Look through the indexes and get the actual first and last digit
        for (size_t i = 0; i < 10; i++) {
            if (idxs[i] != -1 && idxs[i] < minIdx) {
                minIdx = idxs[i];
                firstN = i;
            }
            if (maxidxs[i] > maxIdx) {
                maxIdx = maxidxs[i];
                lastN = i;
            }
        }
        
        sum += (10 * firstN) + lastN;
    }

    cout << "Sum " << sum << "\n";
    infile.close();
}