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--- prelude_to_self-describing_sequence [2011/09/20 06:11] – created jtkorb
+++ prelude_to_self-describing_sequence [2011/09/20 06:28] – jtkorb
@@ Line 1: / Line 1: @@
 ===== Prelude to Self-describing Sequence ======
-First, start by reading the problem statement for [[http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=33&page=show_problem&problem=990|Self-describing Sequence]].  The input format is the same.
+First, start by reading the problem statement for [[http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=33&page=show_problem&problem=990|Self-describing Sequence]].
+For this prelude, create an array, ''fr'', that contains the index of each place in ''f(n)'' where ''f(n)'' changes values (that is, where the next run of identical values appears).
+  n     1   2   3   4   5   6   7   8   9  10  11  12 13 14 15 16
+  f(n)  1   2   2   3   3   4   4   4   5   5   5   6  6  6  6  7
+  fr[n] 1   2   4   6   9  12  16   ...
+This array is a kind of run-length encoding of function ''f(n)''.
 ===== Input =====
-Like Pairsumonious Numbers, the input is a sequence of test cases, one per line.  The first number on the line is N, followed by N*(N-1)/2 additional numbers.
+Input consists of a sequence of integers, one per line.  The last entry is a 0, which should not be processed.
 ===== Output =====
-Print a line of output for each line of input.  The first number on the line is N*(N-1)/2, followed by the N*(N-1)/2 input numbers in sorted order, from lowest to highest.
+For each non-zero input value, ''k'', print the value of ''n'' where ''f(n)'' equals ''k''.
 ===== Sample Input =====