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NWERC11B - Bird tree |
Bird tree
The Bird tree1 is an infinite binary tree, whose first 5 levels look as follows:
It can be defined as follows:
This is a co-recursive definition in which both occurrences of bird refer to the full (infinite) tree. The expression bird + 1 means that 1 is added to every fraction in the tree, and 1∕bird means that every fraction in the tree is inverted (so a∕b becomes b∕a).
Surprisingly, the tree contains every positive rational number exactly once, so every reduced fraction is at a unique place in the tree. Hence, we can also describe a rational number by giving directions (L for left subtree, R for right subtree) in the Bird tree. For example, 2∕5 is represented by LRR. Given a reduced fraction, return a string consisting of L’s and R’s: the directions to locate this fraction from the top of the tree.
Input
On the first line a positive integer: the number of test cases, at most 100. After that per test case:
- one line with two integers a and b (1 ≤ a,b ≤ 109), separated by a ’/’. These represent the numerator and denominator of a reduced fraction. The integers a and b are not both equal to 1, and they satisfy gcd(a,b) = 1.
For every test case the length of the string with directions will be at most 10 000.
Output
Per test case:
- one line with the string representation of the location of this fraction in the Bird tree.
Sample in- and output
Input |
Output |
3 1/2 2/5 7/3 |
L LRR RLLR |
1Hinze, R. (2009). The Bird tree. J. Funct. Program., 19:491–508.
Added by: | Jeroen Bransen |
Date: | 2011-11-02 |
Time limit: | 1s |
Source limit: | 50000B |
Memory limit: | 1536MB |
Cluster: | Cube (Intel G860) |
Languages: | All except: ASM64 |
Resource: | NWERC 2011 Jury |