Add binomialCoefficient

test/binomialCoefficient/binomialCoefficient.js

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+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);
+};
+module.exports = binomialCoefficient;

test/binomialCoefficient/binomialCoefficient.test.js

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+const test = require('tape');
+const binomialCoefficient = require('./binomialCoefficient.js');
+
+test('Testing binomialCoefficient', (t) => {
+  //For more information on all the methods supported by tape
+  //Please go to https://github.com/substack/tape
+  t.true(typeof binomialCoefficient === 'function', 'binomialCoefficient is a Function');
+  t.equal(binomialCoefficient(8, 2), 28, 'Returns the appropriate value');
+  t.equal(binomialCoefficient(0, 0), 1, 'Returns the appropriate value');
+  t.equal(binomialCoefficient(5, 3), 10, 'Returns the appropriate value');
+  t.true(Number.isNaN(binomialCoefficient(NaN, 3)), 'Returns NaN');
+  t.true(Number.isNaN(binomialCoefficient(5, NaN)), 'Returns NaN');
+  //t.deepEqual(binomialCoefficient(args..), 'Expected');
+  //t.equal(binomialCoefficient(args..), 'Expected');
+  //t.false(binomialCoefficient(args..), 'Expected');
+  //t.throws(binomialCoefficient(args..), 'Expected');
+  t.end();
+});