All Flashcards
What is row-major traversal?
Traversing a 2D array by processing all elements in one row before moving to the next row.
What is column-major traversal?
Traversing a 2D array by processing all elements in one column before moving to the next column.
What are nested for loops?
A for loop inside another for loop, commonly used to iterate over 2D arrays.
What is an enhanced for loop?
A simplified for loop syntax for iterating through elements of an array or collection.
What is a 2D array?
An array of arrays, where each element is itself an array, forming rows and columns.
Define linear search.
A method for finding a target value within a list. It sequentially checks each element of the list for the target value until a match is found or until all elements have been searched.
Define pass-by-value.
A method of argument passing in which a copy of the actual parameter's value is made and passed to the called function or method.
What is autoboxing?
The automatic conversion that the Java compiler makes between the primitive types and their corresponding object wrapper classes.
Define mode.
The value that appears most often in a set of data.
Define mean.
The average of a set of numbers.
What does the following code output?
java
int[][] arrayB = {{1, 2}, {3, 4}};
for (int i = 0; i < arrayB.length; i++) {
for (int j = 0; j < arrayB[0].length; j++) {
System.out.print(arrayB[i][j] + " ");
}
}
1 2 3 4
What does the following code output?
java
int[][] arrayB = {{1, 2}, {3, 4}};
for (int i = 0; i < arrayB[0].length; i++) {
for (int j = 0; j < arrayB.length; j++) {
System.out.print(arrayB[j][i] + " ");
}
}
1 3 2 4
Identify the error in the following code:
java
public static void main(str[] args) {
int[][] arrayB = {{1, 2}, {3, 4}};
rowWiseForward(arrayB);
}
The parameter in main should be String[], not str[].
What does the following code output?
java
int[][] arrayB = {{1, 2}, {3, 4}};
int sum = 0;
for (int[] row : arrayB) {
for (int num : row) {
sum += num;
}
}
System.out.println(sum);
10
What does the following code output?
java
int[][] arrayB = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}};
System.out.println(arrayB.length);
3
What does the following code output?
java
int[][] arrayB = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}};
System.out.println(arrayB[0].length);
4
What does the following code output?
java
int[][] arrayB = {{1, 2}, {3, 4}};
System.out.println(arrayB[1][0]);
3
What does the following code output?
java
int[][] arrayB = {{1, 2}, {3, 4}};
int product = 1;
for (int i = 0; i < arrayB.length; i++) {
for (int j = 0; j < arrayB[0].length; j++) {
product *= arrayB[i][j];
}
}
System.out.println(product);
24
What does the following code output?
java
int[][] arrayB = {{1, 2}, {3, 4}};
int max = arrayB[0][0];
for (int i = 0; i < arrayB.length; i++) {
for (int j = 0; j < arrayB[0].length; j++) {
if (arrayB[i][j] > max) {
max = arrayB[i][j];
}
}
}
System.out.println(max);
4
What does the following code output?
java
int[][] arrayB = {{1, 2, 3}, {4, 5, 6}};
int count = 0;
for (int[] row : arrayB) {
for (int num : row) {
if (num % 2 == 0) {
count++;
}
}
}
System.out.println(count);
3
Why are nested loops needed for 2D array traversal?
One loop iterates through the rows, and the other iterates through the columns in each row.
Explain the difference between regular and enhanced for loops when modifying 2D array elements.
Regular for loops access the array directly, allowing modification. Enhanced for loops operate on copies, so modifications don't affect the original array (unless object instance variables are modified).
Why initialize maxValue to array[0][0] instead of 0 when finding the maximum value?
If all array values are negative, initializing to 0 would incorrectly identify 0 as the maximum.
Why can enhanced for loops be used when changing the value of an object's instance variable?
The copy contains references to the actual objects themselves.
What is the significance of 'i < array.length' in 2D array traversal?
It ensures the loop iterates through all rows of the array.
What is the significance of 'i < array[0].length' in 2D array traversal?
It ensures the loop iterates through all columns of the array.
How does the modulo operator help in snaking around?
The modulo operator helps alternate the direction of traversal every row or column.
What is the first step when finding the mode of an array?
Place the numbers into a 1D array.
What is the formula for calculating the mean?
Sum of all elements / (array.length * array[0].length)
What is the difference between finding a sum and finding a mean?
Finding the mean requires one more step, dividing the sum by the total number of elements.