In this problem, we are given a grid of characters and want to expand it by a factor of K in both the horizontal and vertical dimensions.

It's worth noting to begin with that the first K rows that we print can be generated from the first row of the grid, the next K rows will be generated from the second row, and so on. Therefore, we focus our attention only on expanding a single row.

Note that expanding a single row will generate K copies of the same row, so we only need to figure out how to generate a copy of a row that is stretched horizontally by a factor of K.

We can do this though just by printing each character K times.

Here is my Java code.

import java.io.*;
import java.util.*;
public class cowsignal {
	public static void main(String[] args) throws IOException {
		// initialize file I/O
		BufferedReader br = new BufferedReader(new FileReader("cowsignal.in"));
		PrintWriter pw = new PrintWriter(new BufferedWriter(new FileWriter("cowsignal.out")));

		StringTokenizer st = new StringTokenizer(br.readLine());
		int r = Integer.parseInt(st.nextToken());
		int c = Integer.parseInt(st.nextToken());
		int k = Integer.parseInt(st.nextToken());
		
		for(int i = 0; i < r; i++) {
			// get the next row to generate k copies of
			String currRow = br.readLine();
			
			// we will generate the same row K times
			for(int internalRow = 0; internalRow < k; internalRow++) {
				// loop over each character...
				for(int j = 0; j < c; j++) {
					// and print it k times
					for(int a = 0; a < k; a++) {
						pw.print(currRow.charAt(j));
					}
				}
				// we need to print a new line to indicate that we need to go to the next row
				pw.println();
			}
		}
		
		pw.close();
	}
}