Check if The Number is Fascinating — LeetCode 2729 Python Solution

The problem

You are given an integer n that consists of exactly 3 digits. We call the number n fascinating if, after the following modification, the resulting number contains all the digits from 1 to 9 exactly once and does not contain any 0's: Concatenate n with the numbers 2 * n and 3 * n.

Example

Input

n = 192

Output

true

Explanation

We concatenate the numbers n = 192 and 2 * n = 384 and 3 * n = 576. The resulting number is 192384576. This number contains all the digits from 1 to 9 exactly once.

Python solution

class Solution:
    def isFascinating(self, n: int) -> bool:
        s = str(n) + str(2 * n) + str(3 * n)
        return "".join(sorted(s)) == "123456789"

Complexity

Pattern: Math and Number Theory

Find the closed form, the invariant, or the modular identity — and skip the loop entirely. LeetCode 2729. Check if The Number is Fascinating is filed here because LeetCode tags it Math, which is the vocabulary this hub collects.

The math and number theory guide has the Python template for the pattern and the 485 LeetCode problems that use it.

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