Added get divisors function

src/Algorithms.rs

@@ -303,3 +303,76 @@ pub fn getNumPrimesBig(numberOfPrimes: num::BigInt) -> Vec<num::BigInt>{
 	primes.sort();
 	return primes;
 }
+
+//This function returns all the divisors of goalNumber
+pub fn getDivisors(goalNumber: i64) -> Vec<i64>{
+	let mut divisors = Vec::<i64>::new();
+
+	//Start by checking that the number is positive
+	if(goalNumber <= 0){
+		return divisors;
+	}
+	//If the number is 1 return just itself
+	else if(goalNumber == 1){
+		divisors.push(1);
+		return divisors;
+	}
+
+	//Start at 3 and loop through all numbers < sqrt(goalNumber) looking for a number that divides it evenly
+	let topPossibleDivisor = (goalNumber as f64).sqrt().ceil() as i64;
+	let mut possibleDivisor = 1i64;
+	while(possibleDivisor <= topPossibleDivisor){
+		//If you find one add it and the number it creates to the list
+		if((goalNumber % possibleDivisor) == 0){
+			divisors.push(possibleDivisor);
+			//Account for the possibility of sqrt(goalNumber) being a divisor
+			if(possibleDivisor != topPossibleDivisor){
+				divisors.push(goalNumber / possibleDivisor);
+			}
+			//Take care of a few occations where a number was added twice
+			if(divisors.last().unwrap() == &(possibleDivisor + 1)){
+				possibleDivisor += 1;
+			}
+		}
+		possibleDivisor += 1;
+	}
+
+	//Sort the list before returning it (for neatness)
+	divisors.sort();
+	return divisors;
+}
+pub fn getDivisorsBig(goalNumber: num::BigInt) -> Vec<num::BigInt>{
+	let mut divisors = Vec::<num::BigInt>::new();
+	//Start by checking that he number is positive
+	if(goalNumber <= num::BigInt::from(0)){
+		return divisors;
+	}
+	//If the number is 1 return just itself
+	else if(goalNumber == num::BigInt::from(1)){
+		divisors.push(num::BigInt::from(1));
+		return divisors;
+	}
+
+	//Start at 3 and loop through all numbers < sqrt(goalNumber) looking for a number that divides it evenly
+	let topPossibleDivisor = goalNumber.sqrt();
+	let mut possibleDivisor = num::BigInt::from(1);
+	while(&possibleDivisor <= &topPossibleDivisor){
+		//If you find one add it and the number it creates to the list
+		if((&goalNumber % &possibleDivisor) == num::BigInt::from(0)){
+			divisors.push(num::BigInt::new(possibleDivisor.sign(), possibleDivisor.to_u32_digits().1));
+			//Account for the possibility of sqrt(goalNumber) being a divisor
+			if(&possibleDivisor != &topPossibleDivisor){
+				divisors.push(num::BigInt::new((&goalNumber / &possibleDivisor).sign(), (&goalNumber / &possibleDivisor).to_u32_digits().1));
+			}
+			//Take care of a few occations where the number was added twice
+			if(divisors.last().unwrap() == &(&possibleDivisor + num::BigInt::from(1))){
+				possibleDivisor += num::BigInt::from(1);
+			}
+		}
+		possibleDivisor += 1;
+	}
+
+	//Sort the list before returning it (for neatness)
+	divisors.sort();
+	return divisors;
+}

src/lib.rs

@@ -87,6 +87,22 @@ mod AlgorithmsTests{
 		let answer2 = super::Algorithms::getNumPrimesBig(numPrimes2);
 		assert_eq!(correctAnswer2, answer2);
 	}
+	#[test]
+	fn testGetDivisors(){
+		//Test1
+		let mut correctAnswer1 = Vec::<i64>::new();
+		correctAnswer1.extend_from_slice(&[1, 2, 4, 5, 10, 20, 25, 50, 100]);
+		let topNum1 = 100;
+		let answer1 = super::Algorithms::getDivisors(topNum1);
+		assert_eq!(correctAnswer1, answer1);
+
+		//Test2
+		let mut correctAnswer2 = Vec::<num::BigInt>::new();
+		correctAnswer2.extend_from_slice(&[num::BigInt::from(1), num::BigInt::from(2), num::BigInt::from(4), num::BigInt::from(5), num::BigInt::from(10), num::BigInt::from(20), num::BigInt::from(25), num::BigInt::from(50), num::BigInt::from(100)]);
+		let topNum2 = num::BigInt::from(100);
+		let answer2 = super::Algorithms::getDivisorsBig(topNum2);
+		assert_eq!(correctAnswer2, answer2);
+	}
 }