Introduction To Arrays¶

Definition¶

Array is the sequential collection of same types of data. The datatype can be of any type i.e, int, float, char, etc. Below is the declaration of the array:

int arr[] = new int[5];

It can also be declared as:

int[] arr = new int[5]

Here, ‘int’ is the datatype, ‘arr’ is the name of the array and ‘n’ is the size of an array.
We can access all the elements of the array as arr[0], arr[1] ….. arr[n-1].

Note: Array indexing starts with 0.

Question¶

Maximum index of array of size N is ?

Choose the correct answer

Choices

1
0
N-1
N

Question¶

Given an array as arr = {3,4,1,5,1}. What is ths sum of all elements in the array?

Choose the correct answer

Choices

12
13
14
15

Question 1¶

Take an integer array arr of size N as input and print its sum.

TestCase¶

Input¶

N = 5
arr = {1,2,3,4,5}

Output¶

Explanation¶

To calculate the sum of all the elements in the array, we need a variable say sum which is initially zero. Then iterate all the elements and adding them to sum.

PseudoCode¶

int sum = 0;
for (int i = 0; i < n; i++) {
    sum = sum + arr[i];
}
System.out.println("Sum is " + sum);

Question¶

Given an array as arr = {3,4,1,5,1}. Find the maximum element.

Choose the correct answer

Choices

3
4
5
1

Question 2¶

Take an integer array arr of size N as input and print its maximum element.

TestCase¶

Input¶

N = 5
arr = {1,2,3,4,5}

Output¶

PseudoCode¶

int maximum_element = 0;
for (int i = 0; i < n; i++) {
    if (maximum_element < arr[i]) maximum_element = arr[i];
}
system.out.println("Sum is " + maximum_element);

Question¶

What will be the output of the above code with N = 5 arr = {-3, -7, -2, -10, -1} array as input ?

Choose the correct answer

Choices

-7
-1
0
2

Explanation

Initially we have assumed 0 as the max element in the array and in the given case, all the element is smaller than 0. So, the max element is 0.

Question 2 PseudoCode¶

Note: We can fix it by initially assigning arr[0] to the maximum_element. So the updated pseudocode is:

int maximum_element = arr[0];
for (int i = 0; i < n; i++) {
    if (maximum_element < arr[i]) maximum_element = arr[i];
}
system.out.println("Sum is " + maximum_element);

Question 3¶

Take an integer array arr of size N as input and return its minimum element.

TestCase¶

Input¶

N = 5
arr = {1,2,3,4,5}

Output¶

PseudoCode¶

public static int findMin(int arr[], int n) {
    int minimum_element = arr[0];
    for (int i = 0; i < n; i++) {
        if (minimum_element > arr[i]) minimum_element = arr[i];
    }
    return minimum_element;
}

Question 4¶

Take an integer array arr of size N as input and check whether an integer k is present in that or not.

TestCase¶

Input¶

N = 5
arr = {1,2,3,4,5}
k = 4

Output¶

true

Explanation¶

To check whether an integer k is present in the array or not, we need to check each element and compare it with k. If none of the element is equal to k,then return false.

PseudoCode¶

public static boolean findK(int arr[], int n, int k) {
    for (int i = 0; i < n; i++) {
        if (arr[i] == k) return true;
    }
    return false;
}

Question¶

Given an array as arr = {3,4,1,5,1}. What is the frequency of 1?

Frequency of any element is defined as the number of occurences of that element in the array.

Choose the correct answer

Choices

0
1
2
3

Question 5¶

Take an integer array arr of size N as input. Return the frequency of K in the array.

TestCase¶

Input¶

N = 6
arr = {1,2,3,4,5,1}
k = 1

Output¶

Note: Here frequency is the number of times the element k occurs in the array.

PseudoCode¶

public static int frequencyK(int arr[], int n, int k) {
    int frequency = 0;
    for (int i = 0; i < n; i++) {
        if (arr[i] == k) frequency++;
    }
    return frequency;
}

Question 6¶

Given an integer array as an input, return the frequency count of the array.

TestCase¶

Input¶

arr = {1,1,2,1,3,1,3}

Output¶

{4,4,1,4,2,4,2}

PseudoCode¶

int[] frecount(int arr[]) {
    int n = arr.length;
    int[] ans = new int[n];
    for (int i = 0; i < n; i++) {
        ans[i] = frequencyK(arr, n, arr[i]);
    }
    return ans;
}

Question 7¶

Given an integer array as an input, check whether it is strictly increasing.

TestCase¶

Input¶

N = 5
arr = {1,2,3,4,5}

Output¶

true

Explanation¶

All the element in the array is in sorted order. So, we can say that it is in strictly increasing order. As

1 < 2 < 3 < 4 < 5

PseudoCode¶

public static boolean strictlyincreasing(int arr[]) {
    int n = arr.length;
    for (int i = 0; i < n - 1; i++) {
        if (arr[i] >= arr[i + 1]) return false;
    }
    return true;
}