/**
 * Write a description of class LabWeek9 here.
 *
 * @author (your name)
 * @version (a version number or a date)
 */
public class LabWeek9
{
    // returns the largest element in a 
    // e.g. max({{1, 3}, {7, -2, 0}, {4, 4}}) = 7
    public static int max(int[][] a)
    {
        int max = a[0][0];
        for (int[] r : a)
            for (int x : r)
                max = Math.max(max, x);
        return max;
    }

    // returns the sum of the elements in the xth row in a 
    // e.g. rowSum({{3}, {8, -2, 6}, {5, -2}}, 1) = 8 + (-2) + 6 = 12
    public static int rowSum(int[][] a, int x)
    {
        int sum = 0;
        if (0 <= x && x < a.length)
           for (int y : a[x]) 
               sum += y;
        return sum;
    }

    // returns the sum of the elements in the xth column in a
    // e.g. columnSum({{3, 4}, {6}, {0, 8, -2}}, 1) = 4 + 8 = 12 
    public static int columnSum(int[][] a, int x)
    {
        int sum = 0;
        if (0 <= x)
           for (int[] r : a)
               if (x < r.length) 
                  sum += r[x];
        return sum;
    }

    // returns an array holding the sums of the rows in a 
    // e.g. allRowSums({{1}, {2, 3}, {4, 5, 6}}) = {1, 5, 15}
    public static int[] allRowSums(int[][] a)
    {
        int[] sums = new int[a.length];
        for (int i = 0; i < a.length; i++) 
            sums[i] = rowSum(a, i);
        return sums;
    }

    // returns true iff a is square, 
    // i.e. iff every row has the same length as the number of rows 
    public static boolean isSquare(int[][] a)
    {
        for (int[] r : a)
            if (r.length != a.length) 
               return false;
        return true;
    }

}