Number Theory 1 is the introduction: modulo.
Modulo can be used for cryptography and just making your computer not crash in a lot of ways. Its used in a lot more than odd/even number flags :)
Prime
Int only divisible by 1 or itself. Number not prime is composite.
Primes less than 20
{2,3,5,7,11,13,17,19}
Finding Primes - Trial Division
If n is a composite integer, then n a prime divisor less than or equal to
Sieve of Eratosthenes
Used to find all primes not exceeding a specified postive integer.
Find all primes less than 50.
class Solution(object):
def countPrimes(self, n):
if n < 2:
return 0
sieve = [True] * n
sieve[0] = sieve[1] = False
i = 2
while i * i < n:
if sieve[i]:
for j in range(i * i, n, i):
sieve[j] = False
i += 1
return sum(sieve)
Computing Bézout coefficients
i wrote it down srr its not going here.
this note was imported from my other vault, ideas are not complete :(