Question
A confusing number is one that, when each digit is rotated 180 degrees, becomes a different valid number. Only digits 0,1,6,8,9 are rotatable (0->0, 1->1, 6->9, 8->8, 9->6); any number containing 2,3,4,5,7 is not rotatable at all. Rotating reverses the digit order. Given `n`, count how many integers in [1, n] are confusing numbers. 1 <= n <= 1000000000.
confusing_number_ii(n: int) → int[20]out6State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.
Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.