Найти во множестве два числа, которые в разнице дают минимальное число

a = {23, 56, 78, 34, 67, 34, 98, 12, 76, 17, 41, 19, 13, 51, 83, 43, 56}
a1 = a2 = None
difference = float("inf")
for i in range(len(b := sorted(a)) - 1):
    tmp = b[i + 1] - b[i]
    if tmp < difference:
        difference = tmp
        a1, a2 = b[i + 1], b[i]
print(a1, a2)

print(*min(combinations(a, 2), key=lambda x: abs(x[1] - x[0])))

def min_diff(arr):
    size=len(arr)
    mi=abs(arr[0]-arr[1])
    ci=(0,1)
    for i in range(1,size):
        for j in range(i+1,size):
            diff=abs(arr[i]-arr[j])
            if diff < mi:
                mi=diff
                ci=(i,j)
    return mi,ci
    
print(min_diff([6,17,9,12,13]))

a = {23, 56, 78, 34, 67, 34, 98, 12, 76, 17, 41, 19, 13, 51, 83, 43, 56}
b = list(sorted(a))
c = [b[i] - b[i - 1] for i in range(1, len(a))]
d = c.index(min(c))
print(b[d], b[d + 1])

b = sorted(a)
print(min(zip(b[:-1], b[1:]), key = lambda x: x[1]-x[0]))

print(min([(u,v) for i,u in enumerate(a) for j, v in enumerate(a) if i > j]
            , key = lambda x: abs(x[1]-x[0])
        ))