Solution.java

import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

public class Solution {

  // Complete the gridChallenge function below.
  static String gridChallenge(String[] grid) {
    char[][] cache = new char[grid.length][grid[0].length()];
    for (int i = 0; i < grid.length; i++) {
      for (int j = 0; j < grid[i].length(); j++) {
        cache[i][j] = grid[i].charAt(j);
      }
      Arrays.sort(cache[i]);

      if (i != 0) {
        for (int j = 0; j < grid[i].length(); j++) {
          if (cache[i-1][j] > cache[i][j]) {
            return "NO";
          }
        }
      }
    }

    return "YES";
  }

  private static final Scanner scanner = new Scanner(System.in);

  public static void main(String[] args) throws IOException {
    BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

    int t = scanner.nextInt();
    scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

    for (int tItr = 0; tItr < t; tItr++) {
      int n = scanner.nextInt();
      scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

      String[] grid = new String[n];

      for (int i = 0; i < n; i++) {
        String gridItem = scanner.nextLine();
        grid[i] = gridItem;
      }

      String result = gridChallenge(grid);

      bufferedWriter.write(result);
      bufferedWriter.newLine();
    }

    bufferedWriter.close();

    scanner.close();
  }
}