Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Finding the first redundant element in an array - JavaScript
Let’s say, we are required to write a function that returns the index of the very first element that appears at least twice in the array. If no element appears more than once, we have to return -1. We have to do this in constant space (i.e., without utilizing extra memory).
Therefore, let's write the solution for this problem. We will use a for loop to iterate over the array and use the Array.prototype.lastIndexOf() method to check for duplicacy.
Example
Following is the code −
const arr1 = [0, 1, 1, 2, 3, 4, 4, 5];
const firstRedundant = arr => {
for(let i = 0; i < arr.length; i++){
if(arr.lastIndexOf(arr[i]) !== i){
return i;
};
};
return -1;
}
console.log(firstRedundant(arr1)); // 1Output
This will produce the following output in console −
1
Updated on: 18-Sep-2020
113 Views
Advertisements