Provided Code

// All three methods are static in a class named DiverseArray (not shown)
public static int arraySum(int[] arr) {
    /* part (a) */
}
public static int[] rowSums(int[][] arr2D) {
    /* part (b) */
}
public static boolean isDiverse(int[][] arr2D) {
    /* part (c) */
}

Part A — arraySum (2 Points)

Write arraySum(). Return the sum of all values in the 1D array arr.

Check Answer Clear

public static int arraySum(int[] arr)
{
    int sum = 0;
    for (int val : arr)
    {
        sum += val;
    }
    return sum;
}

Part B — rowSums (3 Points)

Write rowSums(). Return a 1D array where element k is the sum of row k of arr2D. Must call arraySum().

Check Answer Clear

public static int[] rowSums(int[][] arr2D)
{
    int[] sums = new int[arr2D.length];
    for (int r = 0; r < arr2D.length; r++)
    {
        sums[r] = arraySum(arr2D[r]);
    }
    return sums;
}

Part C — isDiverse (4 Points)

Write isDiverse(). Return true if no two rows have the same sum. Must call rowSums().

Check Answer Clear

public static boolean isDiverse(int[][] arr2D)
{
    int[] sums = rowSums(arr2D);

    for (int i = 0; i < sums.length - 1; i++)
    {
        for (int j = i + 1; j < sums.length; j++)
        {
            if (sums[i] == sums[j])
                return false;
        }
    }
    return true;
}

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