Problem 7 - Find the 10001st prime.

링크

By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6^th prime is 13.

What is the 10001^st prime number?

python

def isprime(n): if n & 1 == 0: return False for x in range(3, int(n**0.5)+1, 2): if n % x == 0: return False return True count = 1 n = 2 while count < 10001: n = n + 1 if isprime(n): count = count + 1 print n

python - speed up

def isprime(n): if n == 1: return False if n < 4: return True if n & 1 == 0: return False if n < 9: return True if n % 3 == 0: return False r = int(n**0.5) f = 5 while f <= r: if n % f == 0: return False if n % (f + 2) == 0: return False f = f + 6 return True count = 1 n = 2 while count < 10001: n = n + 1 if isprime(n): count = count + 1 print n

드디어 파이썬으로 함수를 사용해 보는구나..