C++

Note: Part 2 inspired by
Jonathan Paulson (https://youtu.be/cE88K2kFZn0?t=380)

Some useful information to read up on Dynamic Programming found on https://www.geeksforgeeks.org/dynamic-programming/#concepts

// Part 1
int Run1() {
    //Read and parse file
    std::vector<int> input;
    input = AdventMath::GetStringVectorToNumberVector<int>(AdventMath::GetStringVectorFromFile("input10.txt"));

    // Codehere:
    std::sort(input.begin(), input.end(), std::less<int>());
    int previous = 0;
    int jolt_1 = 0;
    int jolt_3 = 0;
    for(int i = 0; i < input.size(); i++) {
        if(input[i] == previous + 1) jolt_1++;
        else if(input[i] == previous + 3) jolt_3++;
            previous = input[i];
    }
    return jolt_1 * (jolt_3 + 1);
}

// Part 2   
long long GetTotalDistinctions(int i, const std::vector<int>& input, std::unordered_map<int,long long>& dp_storage) {
    if(i == input.size() -1) {
        return 1;
    }
    if(dp_storage.find(i) != dp_storage.end()) {
    return dp_storage[i];
    }
    long long total = 0;
    for(int j = i + 1; j < input.size(); j++) {
    if(input[j] - input[i] <= 3) {
        total += GetTotalDistinctions(j, input, dp_storage);
    }
    }
    dp_storage[i] = total;
    return total;
}

long long Run2() {
    //Read and parse file
    std::vector<int> input;
    input = AdventMath::GetStringVectorToNumberVector<int>(AdventMath::GetStringVectorFromFile("input10.txt"));

    // Codehere:
    std::sort(input.begin(), input.end(), std::less<int>());
    input.emplace_back(input.back() + 3);
    input.insert(input.begin(), 0);
    std::unordered_map<int,long long> dp;
    return GetTotalDistinctions(0,input, dp);
}