Javascript required
Skip to content Skip to sidebar Skip to footer
Home / Find the Number in Array Hackerrank Solution Java

Find the Number in Array Hackerrank Solution Java

Java2Blog

  • keyboard_arrow_left Previous
    • Next keyboard_arrow_right

Java program to find missing number in an array

If you want to practice data structure and algorithm programs, you can go through data structure and algorithm interview questions.

This is one of basic coding interview question asked in my interviews.

Problem :

You are given an integer array containing 1 to n but one of the number from 1 to n in the array is missing. You need to provide optimum solution to find the missing number. Number can not be repeated in the arry.
For example:

int [ ] arr1 = { 7 , 5 , 6 , 1 , 4 , 2 } ;

Missing numner : 3

int [ ] arr2 = { 5 , 3 , 1 , 2 } ;

Missing numner : 4

Solution:

  1. Find the sum of n number using formula n=n*(n+1)/2
  2. Find the sum of elements present in given array.
  3. Substract (sum of n numbers – sum of elements present in the array).

Java program to find missing number in an array:

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

package org . arpit . java2blog ;

public class MissingNumberMain {

public static void main ( String [ ] args ) {

int [ ] arr1 = { 7 , 5 , 6 , 1 , 4 , 2 } ;

System . out . println ( "Missing number from array arr1: " + missingNumber ( arr1 ) ) ;

int [ ] arr2 = { 5 , 3 , 1 , 2 } ;

System . out . println ( "Missing number from array arr2: " + missingNumber ( arr2 ) ) ;

}

public static int missingNumber ( int [ ] arr )

{

int n = arr . length + 1 ;

int sum = n* ( n + 1 ) / 2 ;

int restSum = 0 ;

for ( int i = 0 ; i < arr . length ; i ++ ) {

restSum += arr [ i ] ;

}

int missingNumber = sum - restSum ;

return missingNumber ;

}

}

When you run above program, you will get below output:

Missing number from array arr1 : 3

Missing number from array arr2 : 4


import_contacts

You may also like:

Loading...


import_contacts

You may also like:

Loading...

Author

Related Posts

  • Find first and last position of element in sorted array

    04 June

    Search for a range Leetcode – Find first and last position of element in sorted array

    Table of ContentsApproach 1 (Using Linear Search)Approach 2 (Using Modified Binary Search-Optimal) In this article, we will look into an interesting problem asked in Coding Interviews related to Searching Algorithms. The problem is: Given a Sorted Array, we need to find the first and last position of an element in Sorted array. This problem is […]

  • 28 March

    Sort an array of 0s, 1s and 2s

    Table of ContentsProblemSolution If you want to practice data structure and algorithm programs, you can go through Java coding interview questions. In this post, we will see how to sort an array of 0s, 1s and 2s.We have already seen a post on sort 0s and 1s in an array. Problem Given an array containing zeroes, […]

  • 04 March

    Check if it is possible to reach end of given Array by Jumping

    Table of ContentsProblemSolution If you want to practice data structure and algorithm programs, you can go through Java coding interview questions.   Problem Given an array with positive integers as elements indicating the maximum length of a jump which can be made from any position in the array. Check if it is possible to have […]

  • 17 February

    Check if Array Elements are Consecutive

    Table of ContentsProblemSolutionProgram to check if Array Elements are Consecutive If you want to practice data structure and algorithm programs, you can go through 100+ data structure and algorithm programs. In this post, we will see how to check if array elements are consecutive. Problem Given an array, we need to check if array contains […]

  • 01 November

    Find the local minima in array

    Table of ContentsProblemSolutionNaive approachEfficient approach If you want to practice data structure and algorithm programs, you can go through Java coding interview questions. In this post, we will see how to find the local minima in the array. Problem An element is local minima if it is less than its neighbors. int [] arr = {10, […]

  • 22 October

    Sliding Window Maximum in java

    Table of ContentsProblemSolution If you want to practice data structure and algorithm programs, you can go through Java coding interview questions. In this post, we will see about Sliding Window Maximum in java Problem Given an Array of integers and an Integer k, Find the maximum element of from all the contiguous subarrays of size K. […]

Find the Number in Array Hackerrank Solution Java

Source: https://java2blog.com/java-program-to-find-missing-number-in-array/