Math

Updated: 2021-12-15

isPrime

public static boolean isPrime(int number) {
    if(number == 1 ){
        return false;
    }
    for (int i = 2; i < number; i++) {
        if (number % i == 0) {
            return false;
        }
    }
    return true;
}

Digital Root

https://en.wikipedia.org/wiki/Digital_root#Congruence_formula

Fibonacci

>>> def fibonacci():
...         a, b = 0, 1
...         while True:
...             yield b
...             a, b = b, a + b
...
>>> c = fibonacci()
>>> c.next()
1
>>> c.next()
1
>>> c.next()
2
>>> c.next()
3
>>> c.next()
5
class Solution {
    public int fibonacci(int n) {
        int a = 0, b = 1;
        while(--n > 0) {
            int c = a + b;
            a = b;
            b = c;
        }
        return a;
    }
}