Write a user-defined function NoTwoThree(int Arr[], int N) in C++, which should display the value of all such

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Q. Write a user-defined function NoTwoThree(int Arr[], int N) in C++, which should display the value of all such elements and their corresponding locations in the array Arr (i.e. the array index), which are not multiples of 2 or 3. N represents the total number of elements in the array Arr, to be checked. Example : If the array Arr contains index: 0 1 2 3 4 value: 25 8 12 49 9 Then the function should display the output as : 25 at location 0 49 at location 3

(OR)

Write a user-defined function ReArrange(int Arr[], int N) in C++, which should swap the contents of the first half locations of the array Arr with the contents of the second half locations. N (which is an even integer) represents the total number of elements in the array Arr. Example : If the array Arr contains the following elements (for N = 6) index: 0 1 2 3 4 5 value: 12 5 7 23 8 10 Then the function should rearrange the array to become index: 0 1 2 3 4 5 value: 23 8 10 12 5 7 NOTE : DO NOT DISPLAY the Changed Array contents. Do not use any other array to transfer the contents of array Arr.

CBSECBSE Class XII Board 2019Subjective· 3mImportance★★★★★

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Part (a)Concept understanding — Linear Search

Imagine you have a stack of exam answer sheets on your desk, and you need to find the one belonging to a student named "Priya." You don't have them sorted alphabetically or by roll number. What do you do? You pick up the first sheet, check the name. Not Priya. You pick up the second, check. Not Priya. You keep going, one by one, until you either find Priya's sheet or reach the bottom of the pile.

That simple, step-by-step checking of each item in order is exactly what Linear Search is in computing. It is the most straightforward way to look for something in a list when you have no other information about how the list is arranged.

The Precise Meaning

In computer science, Linear Search (also called Sequential Search) is an algorithm that checks every element of a list, one after the other, from the beginning to the end, until the desired element is found or the list ends. There is no shortcut, no skipping ahead. It works on any list, whether the items are in order or completely jumbled.

Note

The NCERT textbook (Class 11, Computer Science, Chapter 6) introduces Linear Search as the simplest searching technique. It states that the algorithm "compares the element to be searched with each element of the list one by one" until a match is found or the list is exhausted. This is the exact definition you need for your exams.

Why It Matters

You might think, "Why not just sort the list first and then search faster?" That is a fair question, and it gets to the heart of why Linear Search is still taught and used.

It works on unsorted data. If you have a list of items that is constantly changing — like a live feed of stock prices or a list of new customer registrations — sorting it every time a new item is added is expensive and slow. Linear Search handles this chaos without complaint.
It is incredibly simple to understand and implement. For small lists (say, a list of 20 or 30 items), the difference between Linear Search and a faster method is negligible. The simplicity means there is almost no chance of a programming error.
It is the foundation. Understanding Linear Search teaches you the core idea of "iteration" — doing something repeatedly until a condition is met. This concept is the bedrock of almost every other algorithm you will learn.

The Key Trade-off …

Part (b)Concept understanding — List Stack Operations

Let’s begin with something you already know: a stack of plates in a cafeteria. You can only take the top plate off, and you can only put a new plate on top. You never pull a plate from the middle or the bottom. That everyday action is the core idea behind a stack in computer science — a list where all additions and removals happen at one end, called the top.

Now, in your NCERT textbook for Informatics Practices or Computer Science (Class 11 or 12), when you study List Stack Operations, you are learning how to treat a Python list as if it were that stack of plates. A normal list lets you add or remove items from anywhere. But a stack is a restricted list: you can only work with the most recently added item. This restriction is not a weakness — it is a deliberate design that makes certain tasks simple and fast.

The two fundamental operations are:

Push – adding an element to the top of the stack.
Pop – removing the top element from the stack.

There is also a third operation, Peek (or Top), which just looks at the top element without removing it. And you will often check if the stack is empty before trying to pop.

Note

In Python, you can implement a stack using a list. The append() method acts as push, and pop() (with no argument) acts as pop. Python’s list already has these built-in, so you don’t need to write any special code — you just use the list in a disciplined way.

Why does this matter? Because stacks are everywhere in real computing. When you press the Back button in a web browser, it pops the previous page off a stack of visited pages. When you undo an action in a word processor, it pops the last change off a stack of edits. Even the way your computer calls one function from another uses a stack behind the scenes. So learning stack operations is not just about lists — it is about understanding a pattern that appears again and again. …

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Part (a)

void NoTwoThree(int Arr[], int N) {
    for (int i = 0; i < N; i++)
        if (Arr[i] % 2 != 0 && Arr[i] % 3 != 0)
            cout << Arr[i] << " at location " << i << endl;
}
``` …

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Part (a) traverses the array and prints each element that is a multiple of neither 2 nor 3 together with its index; Part (b) swaps the first-half and second-half elements in place without a second array.

Part (a)

An element must be shown only if it is not a multiple of 2 and not a multiple of 3, i.e. Arr[i]%2 != 0 && Arr[i]%3 != 0.

void NoTwoThree(int Arr[], int N) {
    for (int i = 0; i < N; i++)
        if (Arr[i] % 2 != 0 && Arr[i] % 3 != 0)
            cout << Arr[i] << " at location " << i << endl;
}

Trace on {25,8,12,49,9}: 25 (odd, not /3) → print; 8 (/2) skip; 12 (/2,/3) skip; 49 (not /2, not /3) → print; 9 (/3) skip.

25 at location 0
49 at location 3 …

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Same / Similar Concept — real previous-year questions on the same or a closely similar concept, not this exact question.

CBSE 2023Set 91/41 markMCQ
$Q. Q. 17 and 18 are Assertion (A) and Reasoning (R) based questions. Mark the correct choice as$
(a) Both (A) and (R) are true and (R) is the correct explanation for (A).
(b) Both (A) and (R) are true and (R) is not the correct explanation for (A).
(c) (A) is true but (R) is false.
(d) (A) is false but (R) is true. Assertion (A) : In Python, a stack can be implemented using a list. Reasoning (R) : A stack is an ordered linear list of elements that works on the principle of First In First Out (FIFO).
›Reveal solutionSolution

The assertion is true, but the reasoning is false because a stack follows LIFO, not FIFO.

Let’s take this step by step. The Assertion says that in Python, a stack can be implemented using a list. That is perfectly correct. Python’s built-in list type provides methods like append() to add an element at the end and pop() to remove the last element — exactly the operations needed for a stack. Many textbooks and real-world Python code use lists as stacks, so this part is true. …
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Part (a)

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