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
Rearranging array elements in JavaScript
Problem
JavaScript function that takes in an array of literals, arr, as the first and the only argument. This array contains some duplicates placed adjacently.
Our function should rearrange the elements of the array such that no two elements in the array are equal. Our function should return the rearranged array, given that it's guaranteed that there exists at least one possible way of such arrangement.
For example, if the input to the function is −
const arr = [7, 7, 7, 8, 8, 8];
Then the output should be −
const output = [7, 8, 7, 8, 7, 8];
Output Explanation:
There may be other correct possible rearrangements as well.
Example
The code for this will be −
const arr = [7, 7, 7, 8, 8, 8];
const rearrangeArray = (arr = []) => {
const map = arr.reduce((acc, val) => {
acc[val] = (acc[val] || 0) + 1 return acc;
}, {});
const keys = Object.keys(map).sort((a, b) => map[a] - map[b]);
const res = [];
let key = keys.pop();
for(let i = 0; i < arr.length; i += 2){
if(map[key] <= 0){
key = keys.pop();
};
map[key] -= 1;
res[i] = Number(key);
};
for(let i = 1; i < arr.length; i += 2){
if(map[key] <= 0){
key = keys.pop();
};
map[key] -= 1;
res[i] = Number(key);
};
return res;
};
console.log(rearrangeArray(arr));Output
And the output in the console will be −
[ 8, 7, 8, 7, 8, 7 ]
Updated on: 07-Apr-2021
83 Views
Advertisements