Animal Crossing - Code Optimizer

#include <iostream>
#include <fstream>
#include <vector>
#include <string>

using namespace std;
int calcDistance(string code);

int main(){
    string code;
    const string codeFilename = "codes.txt";
    ifstream infile;

    infile.open(codeFilename);
    if (!infile)
    {
        cout << "The input file does not exist." << endl;
    }
    else
    {
        cout << "Code\t\t\t\t\tDistance" << endl;
        getline(infile, code, '\n');
        while (infile)
        {
            cout << code << "\t\t" << calcDistance(code) << endl;
            getline(infile, code, '\n');
        }

        infile.close();
    }
    system("pause");
    return 0;
}

int calcDistance(string code){
    int distance = 0;
    int yPosition = 1;
    int xPosition = 0;
    int changeX;
    int changeY;

    vector<vector <char>> alphabet{
        { '1', '2', '3', '4', '5', '6', '7', '8', '9' },
        { 'q', 'w', 'e', 'r', 't', 'y', 'u', 'i', 'o', 'p' },
        { 'a', 's', 'd', 'f', 'g', 'h', 'j', 'k', 'l' },
        { 'z', 'x', 'c', 'v', 'b', 'n', 'm' }
    };

    for (int i = 0; i < code.length(); i++){
        for (vector<vector<char>>::size_type j = 0; j < alphabet.size(); j++)
        {
            for (vector<char>::size_type k = 0; k < alphabet[j].size(); k++)
            {
                if (alphabet[j][k] == code[i]){
                    changeX = j - xPosition;
                    changeY = k - yPosition;
                    if (j != xPosition && k != yPosition){
                        if (abs(changeX)>abs(changeY)){
                            //cout << changeX << endl;
                            distance += abs(changeX);
                            yPosition = k;
                            xPosition = j;
                        }
                        else{
                            //cout << changeY << endl;
                            distance += abs(changeY);
                            yPosition = k;
                            xPosition = j;
                        }
                    }

                    else if (j != xPosition){
                        //cout << changeX << endl;
                        distance += abs(changeX);
                        yPosition = k;
                        xPosition = j;
                    }

                    else if (k != yPosition){
                        //cout << changeY << endl;
                        distance += abs(changeY);
                        yPosition = k;
                        xPosition = j;
                    }
                }
            }
        }
    }
    return distance;
}