Cognizant Coding and Programming Round

Question 1

What will be the output of the following Python code?

```python
x = [1, 2, 3]
y = x
y.append(4)
print(x)
```

Accepted Answer

[1, 2, 3, 4]

Answer

In Python, when `y = x` is executed, `y` does not create a new list; instead, it creates a new reference that points to the *same* list object that `x` refers to. Therefore, when `y.append(4)` modifies the list, it modifies the single list object shared by both `x` and `y`. Consequently, printing `x` will display the modified list `[1, 2, 3, 4]`.

Question 2

Which sorting algorithm has the worst-case time complexity of O(n^2)?

Accepted Answer

Bubble Sort

Answer

Bubble Sort is a simple sorting algorithm known for its worst-case time complexity of O(n^2). This occurs when the array is sorted in reverse order, requiring the algorithm to perform the maximum number of comparisons and swaps. While easy to understand, its inefficiency makes it impractical for large datasets compared to more advanced sorting algorithms.

Question 3

What does the following Java code print?

```java
int x = 5;
System.out.println(x++ + ++x);
```

Accepted Answer

12

Answer

The expression `x++` is a post-increment operator, meaning `x`'s current value (5) is used in the expression first, then `x` is incremented to 6. The `++x` is a pre-increment operator, so `x` is incremented first (from 6 to 7), and then its new value (7) is used. Therefore, the calculation becomes `5 + 7`, resulting in 12.

Question 4

What is the purpose of the 'break' statement in a loop?

Accepted Answer

To exit the loop immediately

Answer

The 'break' statement is a control flow statement used to terminate the execution of the innermost loop (e.g., `for`, `while`, `do-while`) or `switch` statement immediately. When encountered, program control jumps to the statement directly following the loop or `switch` block. Its primary purpose is to exit a loop prematurely based on a specific condition.

Question 5

What does the following C++ code snippet do?

```cpp
#include <iostream>
using namespace std;
int main() {
    int x = 10;
    int *ptr = &x;
    cout << *ptr;
    return 0;
}
```

Accepted Answer

Prints the value of x

Answer

In this C++ code, `int *ptr = &x;` declares a pointer `ptr` and initializes it with the memory address of the integer variable `x`. The statement `cout << *ptr;` then uses the dereference operator (`*`) to access the value stored at the memory address pointed to by `ptr`. Therefore, it prints the value of `x`, which is 10.

(Cognizant) Cognizant Test Practice Test

(Cognizant) Cognizant Test Practice Test

Cognizant Coding and Programming Round