HackerRank•Apr 27, 2025

Grid Challenge

Hazrat Ali

HackerRank

Given a square grid of characters in the range ascii[a-z], rearrange elements of each row alphabetically, ascending. Determine if the columns are also in ascending alphabetical order, top to bottom. Return YES if they are or NO if they are not.

Example

The grid is illustrated below.

a b c
a d e
e f g

The rows are already in alphabetical order. The columns a a e, b d f and c e g are also in alphabetical order, so the answer would be YES. Only elements within the same row can be rearranged. They cannot be moved to a different row.

Function Description

Complete the gridChallenge function in the editor below.

gridChallenge has the following parameter(s):

  • string grid[n]: an array of strings

Returns

  • string: either YES or NO

Input Format

The first line contains , the number of testcases.

Each of the next  sets of lines are described as follows:
- The first line contains , the number of rows and columns in the grid.
- The next  lines contains a string of length 

Constraints

Each string consists of lowercase letters in the range ascii[a-z]

Output Format

For each test case, on a separate line print YES if it is possible to rearrange the grid alphabetically ascending in both its rows and columns, or NO otherwise.

Sample Input

STDIN   Function
-----   --------
1       t = 1
5       n = 5
ebacd   grid = ['ebacd', 'fghij', 'olmkn', 'trpqs', 'xywuv']
fghij
olmkn
trpqs
xywuv

Sample Output

YES

Solution
#include <bits/stdc++.h>

using namespace std;

string ltrim(const string &);
string rtrim(const string &);

/*
 * Complete the 'gridChallenge' function below.
 *
 * The function is expected to return a STRING.
 * The function accepts STRING_ARRAY grid as parameter.
 */

string gridChallenge(vector<string> grid) {
     int rows = grid.size();
    for (int i = 0; i < rows; i++) {
        sort(grid[i].begin(), grid[i].end());
    }

   
    int columns = grid[0].size();
    for (int i = 0; i < rows - 1; i++) {
        for (int j = 0; j < columns; j++) {
            if (grid[i][j] > grid[i + 1][j])
                return "NO";
        }
    }
    return "YES";

}

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

    string t_temp;
    getline(cin, t_temp);

    int t = stoi(ltrim(rtrim(t_temp)));

    for (int t_itr = 0; t_itr < t; t_itr++) {
        string n_temp;
        getline(cin, n_temp);

        int n = stoi(ltrim(rtrim(n_temp)));

        vector<string> grid(n);

        for (int i = 0; i < n; i++) {
            string grid_item;
            getline(cin, grid_item);

            grid[i] = grid_item;
        }

        string result = gridChallenge(grid);

        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;
}




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