Data Structure and Algorithms using Java Week 3 Nptel Answers
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Data Structure and Algorithms using Java Week 3 Nptel (July-Dec 2025)
Question 1. Which of the following best describes an array in Java?
a) A collection that stores elements of different data types and resizes dynamically.
b) A fixed-size data structure that stores elements of the same data type in contiguous memory locations.
c) A predefined class in Java that allows dynamic insertion and deletion of elements.
d) A data structure that automatically sorts its elements during insertion.
Question 2. Consider a 2D array in Java declared as: int[][] matrix = new int[3][3];
Which of the following statements is true regarding the memory layout and access order of this array?
a) Java stores 2D arrays in column-major order, where elements in the same column are stored contiguously.
b) Java stores 2D arrays in row-major order, where elements in the same row are stored contiguously.
c) Java guarantees contiguous memory for the entire 2D array in either row-major or column-major order.
d) Java 2D arrays are not stored in any order since they are implemented as a list of linked lists.
Question 3. Which of the following is a valid way to declare and initialize an integer array in Java?
a) int array = new int(5];
b) int[5] array = new int[];
c) int[] array = new int[5];
d) array int[5] = new int[];
Question 4. Which of the following statements about the declaration and initialization of a 2D integer array in Java is true?
a) int[][] arr = new int[2][ ]; creates a 2D array with 2 rows and undefined column sizes
b) int[][ ] arr = new int[][3]; is valid and creates a 2D array with 3 columns and undefined row size.
c) int[][] arr = new int[2][3] { {1, 2, 3}, {4, 5, 6} }; correctly initializes a 2D array with values.
d) In Java, all multidimensional arrays must be rectangular (i.e., all rows must have the same number of columns).
These are Data Structure and Algorithms using Java Week 3 Nptel Answers
Question 5. Which of the following statements about Java’s Spliterator interface is true?
a) A Spliterator can only be used for sequential iteration and does not support parallel processing.
b) A Spliterator allows splitting of data sources to enable parallel processing using trySplit().
c) The Spliterator interface is a subclass of Iterator and inherits all of its methods.
d) A Spliterator must always return the same size estimate regardless of the split.
Question 6. What will be the output of the following Java program?
public class ArrayTest {
public static void main(String[] args) {
int[] numbers = new int[5];
for(int i = 0; i < numbers.length; i++) {
numbers[i] = i * 2;
}
System.out.println(numbers[5]);
}
}
a) 10
b) ArrayIndexOutOfBoundsException
c) 0
d) Compilation Error
Question 7. Which of the following statements about the Vector class in Java is true?
a) Vector is not synchronized and is suitable only for single-threaded environments.
b) Vector automatically shrinks in size when elements are removed.
c) Vector is synchronized and allows dynamic resizing with thread-safe operations.
d) Vector is a subclass of Set and does not allow duplicate elements.
These are Data Structure and Algorithms using Java Week 3 Nptel Answers
Question 8. What will be the output of the following Java program?
public class ArrayMystery {
public static void main(String[] args) {
int[] arr = {1, 2, 3, 4, 5};
int result = 0;
for (int i = 0; i < arr.length; i++) {
arr[i] = arr[i] + i;
}
for (int i = arr.length - 1; i >= 0; i -= 2) {
result += arr[i];
}
System.out.println(result);
}
}
a) 13
b) 15
c) 17
d) 19
Question 9. Which of the following statements about ArrayList in Java is true?
a) ArrayList is synchronized by default and suitable for multithreaded access.
b) ArrayList allows primitive types like int and double without boxing.
c) ArrayList provides constant-time performance for adding or removing elements anywhere in the list.
d) ArrayList maintains the insertion order and allows random access to elements in constant time.
Question 10. What will be the output of the following Java program?
import java.util.ArrayList;
public class ArrayListTest {
public static void main(String[] args) {
ArrayList<String> list = new ArrayList<>();
list.add("A");
list.add("B");
list.add("C");
list.remove("B");
list.add(1, "D");
System.out.println(list);
}
}
a) [A, B, C]
b) [A, D, C]
c) [A, C, D]
d) [A, D, B, C]
Data Structure and Algorithms using Java Week 3 Nptel Answers (July-Dec 2024)
Course Link: Click Here
Session: JUL-DEC 2024
Q1.Which of the following statements about arrays in Java is true?
a. Arrays in Java are dynamic and can change their size after creation.
b. You can store different types of elements (e.g., integers and strings) in the same array in Java.
c. The default value of elements in an array of integers in Java is null.
d. The length of an array in Java can be determined using the length property.
Answer: d. The length of an array in Java can be determined using the length property.
Q2. Which of the following statements is true about the order of elements in the matrix array in Java?
a. Java stores 2D arrays in column-major order, so elements are stored column by column.
b. Java stores 2D arrays in row-major order, so elements are stored row by row.
c. Java allows you to specify whether a 2D array should be stored in row-major or column-major order.
d. Java does not support 2D arrays directly; it only supports arrays of arrays.
Answer: b. Java stores 2D arrays in row-major order, so elements are stored row by row.
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These are Data Structure and Algorithms using Java Week 3 Nptel Answers
Q3. Which of the following is an output of the above program?
a. Charlie
b. Bob
c. Alice
d. Compilation Error
Answer: d. Compilation Error
Q4. Which of the following statements correctly declares an array in Java?
a. int[] numbers = new int();
b. int numbers[] = new int[10];
c. int numbers[10] = new int();
d. int numbers = new int[10]
Answer: b. int numbers[] = new int[10];
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These are Data Structure and Algorithms using Java Week 3 Nptel Answers
Q5. Which of the following statements is true regarding ArrayList in Java?
a. ArrayList is a synchronized data structure, making it thread-safe.
b. ArrayList allows duplicate elements and maintains insertion order.
c. ArrayList has a fixed size that must be specified at creation and cannot be changed.
d. ArrayList can only store primitive data types like int, double, and char
Answer: b. ArrayList allows duplicate elements and maintains insertion order.
Q6.Which of the following is an output of the above program ?
a. It will print numbers from 1 to 5
b. It will print numbers from 1 to 5 and then throw an exception
c. It will compile but not run
d. It will not compile
Answer: b. It will print numbers from 1 to 5 and then throw an exception
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These are Data Structure and Algorithms using Java Week 3 Nptel Answers
Q7.What would be the result of the following code?
import java.util.ArrayList;
public class ArrayListQuestion {
public static void main(String[] args) {
ArrayList<String> colors1 = new ArrayList<>();
colors1.add("red");
colors1.add("green");
colors1.add("blue");
colors1.add("yellow");
ArrayList<String> colors2 = new ArrayList<>(colors1);
colors2.add("orange");
colors2.add("purple");
colors2.add("pink");
System.out.println(colors2.get(5));
}}
a. It will print “purple”
b. It will print “pink”
c. It will print “green”
d. It will throw an exception
Answer: a. It will print “purple”
Q8.What will be the state of the ArrayList after executing the following code?
a. [apple, banana, elderberry, cherry]
b. [apple, banana, elderberry, cherry, date]
c. [apple, elderberry, banana, cherry, date]
d. [apple, banana, cherry, elderberry]
Answer: a. [apple, banana, elderberry, cherry]
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These are Data Structure and Algorithms using Java Week 3 Nptel Answers
Q9.In Java, what is the average time complexity of adding an element to the end of an ArrayList and what is the worst-case time complexity of adding an element to the end of an ArrayList when it requires resizing??
a. Average: O(1), Worst-case: O(n)
b. Average: O(n), Worst-case: O(n log n)
c. Average: O(log n), Worst-case: O(n)
d. Average: O(1), Worst-case: O(1)
Answer: a. Average: O(1), Worst-case: O(n)
Q10.In Java, how can you search for the index of an element in an ArrayList named items and what is the time complexity of this operation?
a. Using items.get(element) with time complexity O(1)
b. Using items.indexOf(element) with time complexity O(n)
c. Using items.binarySearch(element) with time complexity O(log n)
d. Using items.find(element) with time complexity O(n log n)
Answer: b. Using items.indexOf(element) with time complexity O(n)
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These are Data Structure and Algorithms using Java Week 3 Nptel Answers
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