Question 13 Consider the following method intended to swap the first and last rows in a two-dimensional array: public static void swapRow (int[][] a) { /* missing code */ } Which of the following correctly replaces /* missing code */? for (int k = 0; k < a[0].length; k++) { int last = a.length; a[0][k] = a[last][k]; a[last][k] = a [0][k]; } for (int k = 0; k < a[0].length; k++) { int last = a.length - 1; int temp = a [0][k]; a[0][k] = a[last][k]; a[last][k] = temp; } for (int k = 0; k < a[0].length; k++) { int last = a.length; int temp = a [0][k]; a[0][k] = a[last][k]; a[last][k] = temp; } None of the answers listed. for (int k = 0; k < a[0].length; k++) { int last = a.length - 1; a[0][k] = a[last][k]; a[last][k] = a [0][k]; } Question 14 Consider the following method declaration. public static void increment(int[][] a) { for (int r = 0; r < a.length; r++) { for (int c = 0; c < a[0].length; c++) { if (a[r][c] >= 0) { a[r][c]++; } else { a[r][c]--; } } } } Assume the 2D array, matrix, has been initialized to the following values: 4 6 -15 5 11 21 -11 -10 3 4 -10 -18 -21 14 -23 What is the value of matrix after the method call, increment(matrix);? 4 6 -16 5 11 21 -12 -11 3 4 -11 -19 -22 14 -24 5 7 -16 6 12 22 -12 -11 4 5 -11 -19 -22 15 -24 5 7 -14 6 12 22 -10 -9 4 5 -9 -17 -20 15 -22 5 7 -15 6 12 22 -11 -10 4 5 -10 -18 -21 15 -23 4 6 -15 5 11 21 -11 -10 3 4 -10 -18 -21 14 -23 Question 15 Consider the following code. int[][] matrix = new int[4][5]; Suppose we want to initialize matrix to the following rows and columns. 0 1 2 3 4 4 3 2 1 0 0 1 2 3 4 4 3 2 1 0 Which of the options below correctly initializes matrix? I. for (int i = 0; i < matrix.length; i += 2) { for (int j = 0; j < matrix[i].length; j++) { matrix[i][j] = j; matrix[i + 1][j] = j; } } II. for (int i = 0; i < matrix.length; i += 2) { for (int j = 0; j < matrix[i].length; j++) { matrix[i][j] = j; matrix[i + 1][matrix[i].length - j - 1] = j; } } III. for (int i = 0; i < matrix.length; i += 2) { for (int j = 0; j < matrix[i].length; j++) { matrix[i][j] = j; matrix[i + 1][matrix[i].length - j - 1] = i; } } II and III only I only II only I, II and III III only Question 16 Consider the following code: int[][] grid = /* code not shown */; Which of the following could be used to calculate how many cells are in the array? grid.length * grid.length grid.length grid[0].length grid.length * grid[0].length grid.length[0] * grid[0].length Question 17 Consider the following declaration for a two-dimensional array. int[][] grid = new int[3][5]; int c = 0; for (int i = 0; i < grid.length; i++) { for (int j = 0; j < grid[i].length; j++) { grid[i][j] = c; c++; } } What element is displayed when the following line of code is executed? System.out.println(grid[2][1]); 7 10 12 11 6 Question 18 What does the following segment of code do? int[][] a = /* initialization not shown */; int sum = 0; for(int i = 0; i < a.length; i++) { for(int j = 0; j < a[0].length; j++) { if(i % 2 == 0) { sum += a[i][j]; } } } It finds the sum of the elements in the even rows in the array. It finds the sum of every other element in the array. It finds the sum of the elements in the even columns in the array. It finds the sum of all elements in the array. It finds the sum of the even elements in the array. Question 19 Which option best describes what the following algorithm does? int a [][] = /* initialization not shown */; int j = 2; for (int i = 0; i < a[0].length; i++) { int temp = a[j + 1][i]; a[j + 1][i] = a[j][i]; a[j][i] = temp; } Swaps columns 2 and 3. Initializes the values in the array. Swaps rows 2 and 3. Swaps rows 1 and 2. Swaps columns 1 and 2. Question 20 You need a method to find the maximum value in every row of an array. Which of the following methods works as intended? I. public static int[] findMaxList (int a[][]) { int temp [] = new int [a.length]; for(int i = 0; i < a.length; i++) { int max = a[i][0]; for(int j = 0; j < a[0].length; j++) { if (a[i][j] > max) { max = a[0][j]; } } temp [i] = max; } return temp; } II. public static int[] findMaxList (int a[][]) { int temp [] = new int [a.length]; for(int i = 0; i < a.length; i++) { int max = a[i][0]; for(int j =0; j < a[0].length; j++) { if (a[i][j] > max) { max = a[i][j]; } } temp [i] = max; } return temp; } III. public static int[] findMaxList (int a[][]) { int temp [] = new int [a.length]; for(int i = 0; i < a.length; i++) { int max = a[i][0]; for(int j = 0; j < a[0].length; j++) { if(a[i][j] > a[0][j]) { max = a[i][j]; } } temp [i] = max; } return temp; } I only III only II only II and III only I, II and III