Added function to get factorial of number

Algorithms.ts

@@ -642,3 +642,19 @@ export function gcdBig(num1: bigint, num2: bigint){
 	}
 	return num1 | num2;
 }
+
+//Return the factorial of the number passed in
+export function factorial(num: number): number{
+	let fact: number = 1;
+	for(let cnt = 1;cnt <= num;++cnt){
+		fact *= cnt;
+	}
+	return fact;
+}
+export function factorialBig(num: bigint): bigint{
+	let fact: bigint = 1n;
+	for(let cnt = 1n;cnt <= num;++cnt){
+		fact *= cnt;
+	}
+	return fact;
+}

TestAlgorithms.ts

@@ -23,7 +23,7 @@ Copyright (C) 2021  Matthew Ellison
 
 import assert = require("assert");
 import { arrayEquals, getAllFib, getAllFibBig, getFactors, getFactorsBig, getPrimes, getPrimesBig, getNumPrimes, getNumPrimesBig,
-		sqrtBig, getSum, getSumBig, getProd, getProdBig, getDivisors, getDivisorsBig } from "./Algorithms";
+		sqrtBig, getSum, getSumBig, getProd, getProdBig, getDivisors, getDivisorsBig, factorial, factorialBig } from "./Algorithms";
 
 
 function testArrayEquals(){
@@ -205,6 +205,7 @@ function testGetSum(){
 
 	console.log("getSum passed");
 }
+
 function testGetProd(){
 	//Test 1
 	let correctAnswer: number = 0;
@@ -226,6 +227,32 @@ function testGetProd(){
 	console.log("getProd passed");
 }
 
+function testFactorial(){
+	//Test 1
+	let num: number = 1;
+	let correctAnswer: number = 1;
+	let answer: number = factorial(num);
+	assert.ok((correctAnswer == answer), "factorial number 1 failed");
+	//Test 2
+	num = 10;
+	correctAnswer = 3628800;
+	answer = factorial(num);
+	assert.ok((correctAnswer == answer), "factorial number 2 failed");
+	//Test 3
+	num = -5;
+	correctAnswer = 1;
+	answer = factorial(num);
+	assert.ok((correctAnswer == answer), "factorial number 3 failed");
+
+	//Test 4
+	let numBig: bigint = 1n;
+	let correctAnswerBig: bigint = 1n;
+	let answerBig = factorialBig(numBig);
+	assert.ok((correctAnswerBig == answerBig), "factorialBig number 1 failed");
+
+	console.log("factorial passed");
+}
+
 
 //Run all of the tests
 testArrayEquals();
@@ -237,3 +264,4 @@ testGetFactors();
 testGetDivisors();
 testGetSum();
 testGetProd();
+testFactorial();