Online Judge - 11332 - Summing Digits
source_id: UVa
Time Limit: 3 s
Statement
For a positive integer n, let f(n) denote the sum of the digits of n when represented in base 10. It is easy to see that the sequence of numbers $n, f(n), f(f(n)), f(f(f(n)))$, . . . eventually becomes a single digit number that repeats forever. Let this single digit be denoted g(n).
For example, consider $n = 1234567892$.
Then: $$f(n) = 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 2 = 47$$ $$f(f(n)) = 4 + 7 = 11$$ $$f(f(f(n))) = 1 + 1 = 2$$ Therefore, $g(1234567892) = 2.$
Input
Each line of input contains a single positive integer n at most 2,000,000,000. Input is terminated by $n = 0$ which should not be processed.
Output
For each such integer, you are to output a single line containing $g(n)$.
Samples
Input
2 11 47 1234567892 0
Output
2 2 2 2
Discussion
Log in to join the discussion.
Log in
No discussion posts yet.
Recent Submissions
Yogurt
C/C++ · 2026-07-29 18:20