Here are the important Questions for Interviews on Array to understand, if you are going for interview where array questions will be asked then you can read those questions and get answers. Get Important Interview questions on Array here…
Questions for Interviews on Array
What is an array?
An array is a data structure consisting of a collection of elements, each identified by at least one array index or key.
How do you declare an Array?
Each language has its own way of declaring arrays, but the general idea is similar: defining the type of elements and the number of elements or initializing it directly.
C/C++:
int arr[5];
This declares an array of 5 integers in C/C++.
Java:
int[] arr = new int[5];
This declares and initializes an array of 5 integers in Java.
Python:
arr = [1, 2, 3, 4, 5]
In Python, you use a list, which functions like an array, and it doesn’t require a fixed size.
JavaScript:
let arr = [1, 2, 3, 4, 5];
JavaScript uses arrays without needing a size specification at declaration.
C#:
int[] arr = new int[5];
In C#, this declares an array of 5 integers.
Can an array be resized at runtime?
An array is fixed in size once created. However, in C, you can resize an array at runtime using Dynamic Memory Allocation (DMA) with malloc or realloc. Most of the modern languages have dynamic sized arrays like vector in C++, list in Python and ArrayList in Java which automatically get resized.
Is it possible to declare an array without specifying its size?
In C/C++, declaring array without specifying its size is not allowed. Doing so will cause a compile-time error. However we can create a pointer in C and create memory dynamically using malloc(). In C++, we have vectors where we can do declaration first and then dynamically add elements. In modern languages like Java, Python and JavaScript, we can declare without specifying size.
What is the time complexity for accessing an element in an array?
The time complexity for accessing an element in an array is O(1), as it can be accessed directly using its index.
What is the difference between an array and a linked list?
An array is a static data structure, while a linked list is a dynamic data structure. Raw arrays have a fixed size, and elements are stored consecutively in memory, while linked lists can grow and do not require contiguous memory allocation. The dynamic sized arrays allow flexible size, but the worst case time complexity for insertion/deletion at the end becomes more than O(1). With linked list, we get worst case time complexity as O(1) for insertion and deletion.
How would you find out the smallest and largest element in an array?
Best approach is iterative (linear search) while the other two are recursive and sorting approach.
Iterative method
Algorithm:
1.Initialize two variables:
small = arr[0] (first element as the smallest)
large = arr[0] (first element as the largest)
2.Traverse through the array from index 1 to n-1.
3.If arr[i] > large, update large = arr[i].
4.If arr[i] < small, update small = arr[i].
5.Print the values of small and large.
include
using namespace std;
void findMinMax(int arr[], int n) {
int small = arr[0], large = arr[0];
for (int i = 1; i < n; i++) {
if (arr[i] > large)
large = arr[i];
if (arr[i] < small)
small = arr[i];
}
cout << "Smallest element: " << small << endl;
cout << "Largest element: " << large << endl;}
int main() {
int arr[] = {7, 2, 9, 4, 1, 5};
int n = sizeof(arr) / sizeof(arr[0]);
findMinMax(arr, n);
return 0;}
What is the time complexity to search in an unsorted and sorted array?
Unsorted Array: The time complexity for searching an element in an unsorted array is O(n), as we may need to check every element.
Sorted Array : The time complexity for searching an element in a sorted array is O(log n) using binary search
O(logn) takes less time than O(n) whereas O(nlogn) takes more time than O(n).
What are the time complexities to insert and delete at the beginning if we have extra space in the array for the new element?
Insert at Beginning: If we have extra space, the time complexity is O(n), as all the existing elements need to be shifted to make room for the new element.
Delete at Beginning: The time complexity is O(n), as all the remaining elements need to be shifted to fill the gap left by the deleted element.
What are the time complexities to insert and delete at the end if we have extra space in the array for the new element?
Insert at End: If there is extra space, the time complexity is O(1), as we can directly add the element at the end without shifting any other elements.
Delete at End: The time complexity is O(1), as removing the last element does not require shifting any elements
