AoC Day 8 2021

day_8_2021.cpp

#include <stdio.h>
#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

string corrected_wires[] = {"abcefg", "cf", "acdeg", "acdfg", "bcdf", "abdfg", "abdefg", "acf", "abcdefg", "abcdfg"};

vector<string> build_wires(int config[]) {
    vector<string> temp_wires;
    for (int i = 0; i < 10; i++) {
        string temp;
        string current_wire = corrected_wires[i];
        for (int j = 0; j < current_wire.length(); j++)
            temp += ('a' + config[current_wire[j] - 'a']);
        sort(temp.begin(), temp.end());
        temp_wires.push_back(temp);
    }
    return temp_wires;
}

bool valid(int config[], string wires[]) {
    vector<string> broken_wires = build_wires(config);
    for (int i = 0; i < 10; i++) {
        bool exist = false;
        for (int j = 0; j < 10; j++) {
            if (wires[i] == broken_wires[j]) exist = true;
        }
        if (!exist) return false;
    }
    return true;
}

int main() {
  int N = 200, total_small = 0, total_big = 0;
  for (int i = 0; i < N; i++) {
    string wires[10], delimiter, digits[4];
    for (int j = 0; j < 10; j++) {
        cin >> wires[j];
        sort(wires[j].begin(), wires[j].end());
    }
    cin >> delimiter;
    for (int j = 0; j < 4; j++) {
        cin >> digits[j];
        sort(digits[j].begin(), digits[j].end());
        if (digits[j].length() <= 4 || digits[j].length() == 7)
            total_small++;
    }
    // Check the correct mapping between each character
    int checker[] = {0,1,2,3,4,5,6};
    do {
        bool stop = valid(checker, wires);
        if (stop) {
            // Build a correct mapping based on checker
            vector<string> modified_wires = build_wires(checker);
            int temp = 0;
            for (int j = 0; j < 4; j++) {
                temp *= 10;
                for (int k = 0; k < 10; k++) {
                    if  (digits[j] == modified_wires[k]) temp += k;
                }
            }
            total_big += temp;
            break;
        }
    } while(next_permutation(checker, checker+7));

  }
  cout << total_small << " " << total_big << endl;
  return 0;
}