Algorithm find two numbers sum equals given x

a.py

def find_pairs(array, x):
    result = []

    array = sorted(set(array))

    first = 0
    last = len(array) - 1

    while True:
        first_el = array[first]
        last_el = array[last]
        if x == first_el + last_el:
            result.append((first_el, last_el))
            last = last - 1
        elif x > first_el + last_el:
            first = first + 1
        elif x < first_el + last_el:
            last = last - 1
        
        if first == last:
            break
    
    return result


def find_pairs_hash(array, x):
    result = []

    hash = {}
    for i in range(0, len(array)):
        hash[array[i]] = i

    for i in range(0, len(array)):
        el = array[i]
        if (x - el) in hash and hash[x - el] != hash[el]:
            result.append((x - el, el))
    return result

#$ 1-12 5-8
a = [1,2,3,5,7,8,9,12,15]

print("simple")
for x in find_pairs(a, 13):
    print(x)

print("hash")
for x in find_pairs_hash(a, 13):
    print(x)