36 lines
863 B
C++
36 lines
863 B
C++
#include "recursion.hpp"
|
|
|
|
namespace functions {
|
|
|
|
auto fibonacci(const int n) -> long long {
|
|
if (n == 0) return 0;
|
|
if (n == 1) return 1;
|
|
return fibonacci(n - 1) + fibonacci(n - 2);
|
|
}
|
|
|
|
auto sum_digits(const int n) -> int {
|
|
if (n < 10) return n;
|
|
return n % 10 + sum_digits(n / 10);
|
|
}
|
|
|
|
// Advanced recursion with recursive lambda helper
|
|
auto is_palindrome(const int n) -> bool {
|
|
auto f = [](const auto& self, const int x, const int d) -> bool {
|
|
if (x < 0) return false;
|
|
if (x < 10) return true;
|
|
if (x / d != x % 10) return false;
|
|
if (d < 10) return true;
|
|
const int m = (x / d) / 10;
|
|
return self(self, m, d / 100);
|
|
};
|
|
if (n < 0) return false;
|
|
if (n < 10) return true;
|
|
int d = 1;
|
|
while (n / d >= 10) {
|
|
d *= 10;
|
|
}
|
|
return f(f, n, d);
|
|
}
|
|
|
|
} // namespace functions
|