find_sum.py

def merge(A, p, q, r):
    L = A[p:q + 1]
    R = A[q + 1: r + 1]
    i = j = 0
    for k in range(p, r + 1):
        if i == len(L):
            A[k] = R[j]
            j += 1
        elif j == len(R):
            A[k] = L[i]
            i += 1
        elif L[i] <= R[j]:
            A[k] = L[i]
            i += 1
        else:
            A[k] = R[j]
            j += 1


def merge_sort(A, p, r):
    if p < r:
        q = (p + r) // 2
        merge_sort(A, p, q)
        merge_sort(A, q + 1, r)
        merge(A, p, q, r)


def find_sum(S, x):
    merge_sort(S, 0, len(S) - 1)

    left = 0
    right = len(S) - 1
    while left <= right:
        Sum = S[left] + S[right]
        if Sum > x:
            right -= 1
        elif Sum < x:
            left += 1
        else:
            print("Items are {0} and {1}".format(S[left], S[right]))
            right -= 1
            left += 1


def main():
    S = [1, 3, 9, 6, 7, 5, 4, 10]
    x = 8
    print(S)
    find_sum(S, x)


if __name__ == "__main__":
    main()