binomialCoefficient.md

title	tags	author_title	author_url	author_image_url	description	image
binomialCoefficient	math,intermediate	Deepak Vishwakarma	https://github.com/deepakshrma	https://avatars2.githubusercontent.com/u/7682731?s=400	Implementation of "binomialCoefficient" in typescript, javascript and deno.	https://www.positronx.io/wp-content/uploads/2018/11/positronx-banner-1152-1.jpg

Evaluates 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.

const binomialCoefficient = (n: number, k: number): number => {
  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);
};

binomialCoefficient(8, 2); // 28
const result = binomialCoefficient(8, 2);
assertEquals(result, 28);