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 cavityMap function below.
    static String[] cavityMap(String[] grid) {
        ArrayList<Integer> x = new ArrayList<Integer>();
        ArrayList<Integer> y = new ArrayList<Integer>();
        for (int i = 1; i < grid.length - 1; i++) {
            for (int j = 1; j < grid[i].length() - 1; j++) {
                // store top,bottom,left and right characters
                Character c = grid[i].charAt(j);
                Character t = grid[i - 1].charAt(j);
                Character b = grid[i + 1].charAt(j);
                Character l = grid[i].charAt(j - 1);
                Character r = grid[i].charAt(j + 1);
                // if the character is greater than it's adjacent elements, note it's index
                // in the new arraylist
                if (c > t && c > b && c > l && c > r) {
                    x.add(i);
                    y.add(j);
                }
            }
        }
        // replace those places with X in the grid
        for (int i = 0; i < x.size(); i++) {
            grid[x.get(i)] = grid[x.get(i)].substring(0, y.get(i)) + "X"
                    + grid[x.get(i)].substring(y.get(i) + 1, grid[x.get(i)].length());
        }
        return grid;
    }

    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 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 = cavityMap(grid);

        for (int i = 0; i < result.length; i++) {
            bufferedWriter.write(result[i]);

            if (i != result.length - 1) {
                bufferedWriter.write("\n");
            }
        }

        bufferedWriter.newLine();

        bufferedWriter.close();

        scanner.close();
    }
}