Confusing Number Python Solution with Tests

LeetCode 1056, Easy. Topics: Math. View on LeetCode. Generate this problem as a practice environment: tested reference solution, 61 parametrized pytest cases, and a playground notebook:

lcpy gen -n 1056   # by problem number
lcpy gen -s confusing_number   # by problem name

Problem

A confusing number is a number that when rotated 180 degrees becomes a different number with each digit valid. We can rotate digits of a number by 180 degrees to form new digits.

When 0, 1, 6, 8, and 9 are rotated 180 degrees, they become 0, 1, 9, 8, and 6 respectively.
When 2, 3, 4, 5, and 7 are rotated 180 degrees, they become invalid.

Note that after rotating a number, we can ignore leading zeros.

For example, after rotating 8000, we have 0008 which is considered as just 8.

Given an integer n, return true if it is a confusing number*, or* false otherwise.

Examples

Input: n = 6
Output: true
Explanation: We get 9 after rotating 6, 9 is a valid number, and 9 != 6.

Input: n = 89
Output: true
Explanation: We get 68 after rotating 89, 68 is a valid number and 68 != 89.

Input: n = 11
Output: false
Explanation: We get 11 after rotating 11, 11 is a valid number but the value remains the same, thus 11 is not a confusing number.

Constraints

0 <= n <= 10^9

Solution

Reference implementation from solution.py on GitHub, full suite in test_solution.py:

class Solution:
    # Time: O(log10 n)
    # Space: O(1)
    def confusing_number(self, n: int) -> bool:
        rotated = [0, 1, -1, -1, -1, -1, 9, -1, 8, 6]
        x, y = n, 0
        while x:
            x, digit = divmod(x, 10)
            if rotated[digit] < 0:
                return False
            y = y * 10 + rotated[digit]
        return y != n

Complexity

Time	Space
O(log10 n)	O(1)

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Confusing Number Python Solution with Tests

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