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Provided Code

public class ArrayResizer
{
    /** Returns true if all elements in row r of array2D are non-zero. */
    public static boolean isNonZeroRow(int[][] array2D, int r)
    { /* to be implemented in part (a) */ }
    /** Returns the number of rows with all non-zero values. */
    public static int numNonZeroRows(int[][] array2D)
    { /* implementation not shown */ }
    /** Returns a new 2D array containing only rows with no zeros.
     *  Precondition: at least one row with no zeros exists. */
    public static int[][] resize(int[][] array2D)
    { /* to be implemented in part (b) */ }
}

Part A — 4 Points

Write isNonZeroRow: return true if and only if every element in row r of array2D is non-zero.

Write Your Solution

Check Answer   Clear

public static boolean isNonZeroRow(int[][] array2D, int r)
{
    for (int c = 0; c < array2D[r].length; c++)
    {
        if (array2D[r][c] == 0)
        {
            return false;
        }
    }
    return true;
}

Part B — 5 Points

Write resize: return a new 2D array containing only the rows from array2D that have no zero values, in the same order. Must use both numNonZeroRows and isNonZeroRow.

Write Your Solution

Check Answer   Clear

public static int[][] resize(int[][] array2D)
{
    int newRows = numNonZeroRows(array2D);
    int[][] result = new int[newRows][array2D[0].length];
    int nextRow = 0;
    for (int r = 0; r < array2D.length; r++)
    {
        if (isNonZeroRow(array2D, r))
        {
            result[nextRow] = array2D[r];
            nextRow++;
        }
    }
    return result;
}

Common Mistakes to Avoid

int[][] result = new int[array2D.length][array2D[0].length];

int[][] result = new int[numNonZeroRows(array2D)][array2D[0].length];

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