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
Using operations to produce desired results in JavaScript
Problem
We are required to write a JavaScript function that takes in an array of exactly 4 numbers, arr, as the first argument and a target as the second argument.
Our function need to judge whether the numbers in the array arr could operated through *, /, +, -, (, ) to get the value equal to target.
For example, if the input to the function is
Input
const arr = [5, 3, 2, 1]; const target = 4;
Output
const output = true;
Output Explanation
Because we can achieve 4 like this −
(5 - 1) * (3 - 2) = 4
Example
Following is the code −
const arr = [5, 3, 2, 1];
const target = 4;
const canOperate = (arr = [], target = 1) => {
const isValid = x => Math.abs(x - target) < 0.0000001
const helper = (arr = []) => {
if (arr.length === 1) {
return isValid(arr[0])
}
let valid = false
for (let i = 0; i < arr.length; i++) {
for (let j = i + 1; j < arr.length; j++) {
const nextArr = arr.filter((x, index) => index !== i && index !== j)
valid = valid || helper([...nextArr, arr[i] + arr[j]])
|| helper([...nextArr, arr[i] - arr[j]])
|| helper([...nextArr, arr[j] - arr[i]])
|| helper([...nextArr, arr[i] * arr[j]])
|| helper([...nextArr, arr[i] / arr[j]])
|| helper([...nextArr, arr[j] / arr[i]])
}
}
return valid
}
return helper(arr)
}
console.log(canOperate(arr, target));Output
true
Updated on: 24-Apr-2021
46 Views
Advertisements