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Update double_factorial.cpp

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DarkWarrior703 2020-04-25 22:37:50 +03:00 committed by GitHub
parent 9fef832f57
commit b403487142
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1 changed files with 4 additions and 4 deletions
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8
math/double_factorial.cpp
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@ -8,8 +8,8 @@ that have the same parity (odd or even) as n.
It is also called as semifactorial
of a number and is denoted by !! */
uint64_t double_factorial_iterative(unsigned int n){
unsigned long long res = 1;
uint64_t double_factorial_iterative(uint64_t n) {
uint64_t res = 1;
for ( unsigned long long i = n; i >= 0; i -= 2 ) {
if (i == 0 || i == 1) return res;
res *= i;
@ -18,13 +18,13 @@ uint64_t double_factorial_iterative(unsigned int n){
/* Recursion can be costly for large numbers */
uint64_t double_factorial_recursive(unsigned int n){
uint64_t double_factorial_recursive(uint64_t n) {
if (n <= 1) return 1;
return n * double_factorial_recursive(n - 2);
}
int main() {
int n{};
uint64_t n{};
std::cin >> n;
assert(n >= 0);
std::cout << double_factorial_iterative(n);