Submission #3727079

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Source Code Expand

from functools import lru_cache

A, B = input().split()

@lru_cache(maxsize=1000)
def f(k, tight, ban, X):
    if k == len(X):
        return int(ban)

    digit = int(X[k])
    lim = digit if tight else 9
    res = 0
    for i in range(lim+1):
        res += f(k+1, tight and digit==i, ban or i==4 or i==9, X)
        # res += f(k+1, digit==i, ban or i==4 or i==9, X)

    return res

print(f(0, True, False, B) -f(0, True, False, str(int(A)-1)))

Submission Info

Judge Result