Digit Chains
Challenge on lesson: Checkpoint — Recursion
CHALLENGE
Difficulty: intermediate+25 XP
**Description:** Define f(n): the number of steps to reduce n to a single digit,
where one step replaces n by the sum of its digits (a single-digit n needs
0 steps). Answer q queries: f(n) for each.
**Input:** Line 1: q (1 <= q <= 10^5). Next q lines: n (0 <= n <= 10^18).
**Output:** q lines — f(n) for each query.
**Example:** 9875 -> 3 (9875 -> 29 -> 11 -> 2).
Press Submit to check your solution.
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