prime2017.py

def isprime(n):
    for i in range(2, n):
        if n % i == 0:
            return False
    return True


class Counter:
    def __init__(self, n):
        self.prepare_prime(n)
        self.prepare_sum()

    def prepare_prime(self, n):
        self.primes = [p for p in range(2, n+1) if isprime(p)]

    def prepare_sum(self):
        xs = {}
        s = 0
        for i, p in enumerate(self.primes):
            s += p
            xs[i] = s
        self.sums = xs


    def skip(self, nth, rest):
        while self.primes[nth] > rest:
            nth -= 1
            if nth < 0:
                return 0
        return self.count(nth, rest)

    def count(self, nth, rest):
        print(nth, self.primes[nth], rest)
        if nth == 0:
            return rest == self.primes[nth]
        if nth < 0:
            return 0
        if rest < 0:
            return 0
        if rest == 1:
            return 0
        if rest == 0:
            return 1
        return self.count(nth-1, rest)  + self.skip(nth, rest - self.primes[nth])

    def run(self, x):
        return self.count(self.primes.index(x), x)