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Modified number_of_divisors.cpp

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Mann Mehta
2020-04-15 09:10:00 +05:30
parent 6c20a62a9b
commit 4da35f1edf
1 changed files with 17 additions and 9 deletions
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26
math/number_of_divisors.cpp
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@@ -12,11 +12,11 @@
*
* Example:- N=36
* 36 = (3^2 * 2^2)
* number-of-divisors(36) = (2+1) * (2+1) = 9.
* list of divisors of 36 = 1, 2, 3, 4, 6, 9, 12, 18, 36.
* number_of_positive_divisors(36) = (2+1) * (2+1) = 9.
* list of positive divisors of 36 = 1, 2, 3, 4, 6, 9, 12, 18, 36.
**/
int number_of_divisors(int n) {
int number_of_positive_divisors(int n) {
std::vector<int> prime_exponent_count;
for (int i=2; i*i <= n; i++) {
int prime_count = 0;
@@ -28,20 +28,28 @@ int number_of_divisors(int n) {
prime_exponent_count.push_back(prime_count);
}
}
if(n > 1) {
prime_exponent_count.push_back(1);
}
int divisors_count = 1;
// If n is prime at that time vector prime_exponent_count will remain empty.
for (int i=0; i < prime_exponent_count.size(); i++) {
divisors_count = divisors_count * (prime_exponent_count[i]+1);
}
if (divisors_count == 1 && n != 1) {
// Prime number has exactly 2 divisors 1 and itself.
divisors_count = 2;
}
return divisors_count;
}
int main() {
int n;
std::cin >> n;
std::cout << number_of_divisors(n) << std::endl;
if(n < 0) {
n = -n;
}
if(n == 0) {
std::cout << "All non-zero numbers are divisors of 0 !" << std::endl;
} else {
std::cout << "Number of positive divisors is : " << number_of_positive_divisors(n) << std::endl;
}
}