Prime Sum

 Given an even number (greater than 2), return two prime numbers whose sum will be equal to given number.

NOTE: A solution will always exist.

Example:

Input : 4
Output: 2 + 2 = 4

If there are more than one solutions possible, return the lexicographically smaller solution.

If [a, b] is one solution with a <= b,
and [c,d] is another solution with c <= d, then

[a, b] < [c, d]

If a < c OR a==c AND b < d.




Solution:



class Solution:                                             

    def primesum(self, A):

        # write your method here

        i = 2

        primesum = []

        while (i <= A - i):


            if isprime(A - i):

                primesum.append(i)

                primesum.append(A - i)

                return primesum

            i = nextprime(i)

                

        


def isprime(k):


    for i in range(2,int(k/2)):

        if k % i == 0:

          

            return 0

    return 1


def nextprime(k):

    

    while True:

        k =k+1

        if isprime(k):

            return k

  


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