Count numbers with digit gap
Count how many integers in the inclusive range [1, n] have the property that every pair of adjacent decimal digits differs by at least 2 (i.e. |d_i - d_{i+1}| >= 2 for all consecutive digits, reading the number with no leading zeros). Single-digit numbers trivially qualify since they have no adjacent pair. Return the count. 1 <= n <= 10^9.
Implement
count_diff_at_least_two(n: int) → intExamples
in
[20]out17What a strong answer looks like
State 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.
0:00 of about 35 min
solution.py
InputExpectedGot
[20]17not run yetsample