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SPOJ Problem Set (classical)
3934. Recaman’s Sequence
Problem code: MRECAMAN
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The Recaman’s sequence is defined by a0 = 0 ; for m > 0, a(m) = a(m−1) − m if the resulting a(m) is positive and not already in the sequence, otherwise a(m) = a(m−1) + m. The first few numbers in the Recaman’s Sequence is 0, 1, 3,6, 2, 7, 13, 20, 12, 21, 11, 22, 10, 23, 9 · · · .
Given k, your task is to calculate ak.
Input
The input consists of several test cases. Each line of the input contains an integer k where 0 ≤ k ≤ 500000. The last line contains an integer −1, which should not be processed.
Sample Input
7
10000
-1
Output
For each k given in the input, print one line containing ak to the output.
Sample output
20
18658
| Added by: | ~!(*(@*!@^& |
| Date: | 2009-02-23 |
| Time limit: | 1s-5s |
| Source limit: | 50000B |
| Languages: | All except: ERL TECS JS |
| Resource: | Pre Shanghai 2004 |
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