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
Joining strings to form palindrome pairs in JavaScript
Problem
We are required to write a JavaScript function that takes in an array of strings as the only argument. The function is supposed to return an array of arrays of all the index pairs joining the strings at which yields a new palindrome string.
For example, if the input to the function is −
const arr = ['tab', 'cat', 'bat'];
Then the output should be −
const output = [[0, 2], [2, 0]];
Output Explanation:
Because both the strings ‘battab’ and ‘tabbat’ are palindromes.
Example
The code for this will be −
const arr = ['tab', 'cat', 'bat'];
const isPalindrome = (str = '') => {
let i = 0;
let j = str.length - 1;
while (i < j) {
if (str[i] != str[j]) return false;
i++;
j--;
};
return true;
};
const palindromePairs = (arr = []) => {
const res = [];
for (let i = 0; i < arr.length; i++) {
for (let j = i + 1; j < arr.length; j++) {
if (isPalindrome(arr[i] + arr[j])) {
res.push([i, j])
}
if (isPalindrome(arr[j] + arr[i])) {
res.push([j, i])
};
};
};
return res;
};
console.log(palindromePairs(arr));Code Explanation
We have here used a helper function isPalindome() to check whether a string is palindrome or not and our main function uses all combinations to generate all possible pairs and the ones the match our conditions, their index is pushed in the res array.
Output
And the output in the console will be −
[ [ 0, 2 ], [ 2, 0 ] ]
Updated on: 19-Mar-2021
190 Views
Advertisements