Project Euler : Greatest Product of 4 Numbers In A 20×20 Grid

This is the 11th problem from Project Euler and I have used brute force to solve it.

Brute force:

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class Problem_11 {
	private static int s_gridSize = 20;

	public int getMaxProduct(int[][] numberGrid) {
		int maxProduct = 0;

		for (int i = 0; i < Problem_11.s_gridSize; i++)
			for (int j = 0; j < Problem_11.s_gridSize; j++) {
				int max = getMax(new int[] { getHorizontalProduct(i, j, numberGrid),
				        getVerticalProdut(i, j, numberGrid), getDiagonalProductA(i, j, numberGrid),
				        getDiagonalProductB(i, j, numberGrid) });
				if (max > maxProduct)
					maxProduct = max;
			}

		return maxProduct;
	}

	private int getHorizontalProduct(int iIndex, int jIndex, int[][] numberGrid) {
		if (iIndex > Problem_11.s_gridSize - 4)
			return 0;
		else
			return numberGrid[iIndex][jIndex] * numberGrid[iIndex + 1][jIndex] * numberGrid[iIndex + 2][jIndex]
			        * numberGrid[iIndex + 3][jIndex];
	}

	private int getVerticalProdut(int iIndex, int jIndex, int[][] numberGrid) {
		if (jIndex > Problem_11.s_gridSize - 4)
			return 0;
		else
			return numberGrid[iIndex][jIndex] * numberGrid[iIndex][jIndex + 1] * numberGrid[iIndex][jIndex + 2]
			        * numberGrid[iIndex][jIndex + 3];
	}

	private int getDiagonalProductA(int iIndex, int jIndex, int[][] numberGrid) {
		if (iIndex > Problem_11.s_gridSize - 4 || jIndex > Problem_11.s_gridSize - 4)
			return 0;
		else
			return numberGrid[iIndex][jIndex] * numberGrid[iIndex + 1][jIndex + 1] * numberGrid[iIndex + 2][jIndex + 2]
			        * numberGrid[iIndex + 3][jIndex + 3];
	}

	private int getDiagonalProductB(int iIndex, int jIndex, int[][] numberGrid) {
		if (iIndex > Problem_11.s_gridSize - 4 || jIndex < 3)
			return 0;
		else
			return numberGrid[iIndex][jIndex] * numberGrid[iIndex + 1][jIndex - 1] * numberGrid[iIndex + 2][jIndex - 2]
			        * numberGrid[iIndex + 3][jIndex - 3];
	}

	private int getMax(int... numbers) {
		int max = numbers[0];
		for (int i = 1; i < numbers.length; i++)
			if (numbers[i] > max)
				max = numbers[i];
		return max;
	}

	public static int[][] getNumbersGrid(String fileName) throws IOException {
		BufferedReader bufferedReader = new BufferedReader(new FileReader(fileName));

		int[][] numberGrid = new int[Problem_11.s_gridSize][];

		for (int i = 0; i < Problem_11.s_gridSize; i++) {
			numberGrid[i] = new int[Problem_11.s_gridSize];
			String[] nums = bufferedReader.readLine().split(" ");
			for (int j = 0; j < Problem_11.s_gridSize; j++)
				numberGrid[i][j] = Integer.parseInt(nums[j]);

		}

		return numberGrid;
	}

	public static void main(String[] args) throws IOException {
		String fileName = "problem_11.in";
		System.out.println(new Problem_11().getMaxProduct(Problem_11.getNumbersGrid(fileName)));
	}
}

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