Day-12 DSA- Hourglass problem in 2D Array

#include <bits/stdc++.h>

using namespace std;

string ltrim(const string &);
string rtrim(const string &);
vector<string> split(const string &);

/*
 * Complete the 'hourglassSum' function below.
 *
 * The function is expected to return an INTEGER.
 * The function accepts 2D_INTEGER_ARRAY arr as parameter.
 */

int hourglassSum(vector<vector<int>> arr) {
    
    int result = INT_MIN;
    int sum=0;
    for (int r=0; r<=3;++r)
    {
        for(int c=0; c<=3; ++c)
        {
            sum= arr[r][c]+arr[r][c+1]+arr[r][c+2]+arr[r+1][c+1]+
            arr[r+2][c]+arr[r+2][c+1]+arr[r+2][c+2];
            
            result = std::max(result, sum);
        }
    }
    return result;

}

int main()
{
    ofstream fout(getenv("OUTPUT_PATH"));

    vector<vector<int>> arr(6);

    for (int i = 0; i < 6; i++) {
        arr[i].resize(6);

        string arr_row_temp_temp;
        getline(cin, arr_row_temp_temp);

        vector<string> arr_row_temp = split(rtrim(arr_row_temp_temp));

        for (int j = 0; j < 6; j++) {
            int arr_row_item = stoi(arr_row_temp[j]);

            arr[i][j] = arr_row_item;
        }
    }

    int result = hourglassSum(arr);

    fout << result << "\n";

    fout.close();

    return 0;
}

string ltrim(const string &str) {
    string s(str);

    s.erase(
        s.begin(),
        find_if(s.begin(), s.end(), not1(ptr_fun<int, int>(isspace)))
    );

    return s;
}

string rtrim(const string &str) {
    string s(str);

    s.erase(
        find_if(s.rbegin(), s.rend(), not1(ptr_fun<int, int>(isspace))).base(),
        s.end()
    );

    return s;
}

vector<string> split(const string &str) {
    vector<string> tokens;

    string::size_type start = 0;
    string::size_type end = 0;

    while ((end = str.find(" ", start)) != string::npos) {
        tokens.push_back(str.substr(start, end - start));

        start = end + 1;
    }

    tokens.push_back(str.substr(start));

    return tokens;
}