w3resource

JavaScript: Evaluate the binomial coefficient of two integers n and k

JavaScript fundamental (ES6 Syntax): Exercise-260 with Solution

Write a JavaScript program to evaluate the binomial coefficient of two integers n and k.

  • Use Number.isNaN() to check if any of the two values is NaN.
  • Check if k is less than 0, greater than or equal to n, equal to 1 or n - 1 and return the appropriate result.
  • Check if n - k is less than k and switch their values accordingly.
  • Loop from 2 through k and calculate the binomial coefficient.
  • Use Math.round() to account for rounding errors in the calculation.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2 
const binomialCoefficient = (n, k) => {
  if (Number.isNaN(n) || Number.isNaN(k)) return NaN;
  if (k < 0 || k > n) return 0;
  if (k === 0 || k === n) return 1;
  if (k === 1 || k === n - 1) return n;
  if (n - k < k) k = n - k;
  let res = n;
  for (let j = 2; j <= k; j++) res *= (n - j + 1) / j;
  return Math.round(res);
};
console.log(binomialCoefficient(8, 2));

Sample Output:

28

Flowchart:

flowchart: Evaluate the binomial coefficient of two integers n and k.

Live Demo:

See the Pen javascript-basic-exercise-260-1 by w3resource (@w3resource) on CodePen.


Improve this sample solution and post your code through Disqus

Previous: Write a JavaScript program to decode a string of data which has been encoded using base-64 encoding.
Next: Write a JavaScript program that will return true if the bottom of the page is visible, false otherwise.

What is the difficulty level of this exercise?

Test your Programming skills with w3resource's quiz.



JavaScript: Tips of the Day

How to check whether a string contains a substring in JavaScript?

ECMAScript 6 introduced String.prototype.includes:

const string = "foo";
const substring = "oo";

console.log(string.includes(substring));

includes doesn't have Internet Explorer support, though. In ECMAScript 5 or older environments, use String.prototype.indexOf, which returns -1 when a substring cannot be found: 

var string = "foo";
var substring = "oo";

console.log(string.indexOf(substring) !== -1);

Ref: https://bit.ly/3fFFgZv