Dr. Ellie Arroway has established contact with an extraterrestrial civilization. However, all efforts to decode
their messages have failed so far because, as luck would have it, they have stumbled upon a race of stuttering
aliens! Her team has found out that, in every long enough message, the most important words appear
repeated a certain number of times as a sequence of consecutive characters, even in the middle of other
words. Furthermore, sometimes they use contractions in an obscure manner. For example, if they need to
say bab twice, they might just send the message babab, which has been abbreviated because the second b of
the first word can be reused as the first b of the second one.
Thus, the message contains possibly overlapping repetitions of the same words over and over again. As
a result, Ellie turns to you, S.R. Hadden, for help in identifying the gist of the message.
Given an integer m, and a string s, representing the message, your task is to find the longest substring of
s that appears at least m times. For example, in the message baaaababababbababbab, the length-5 word babab
is contained 3 times, namely at positions 5, 7 and 12 (where indices start at zero). No substring appearing
3 or more times is longer (see the first example from the sample input). On the other hand, no substring
appears 11 times or more (see example 2).
In case there are several solutions, the substring with the rightmost occurrence is preferred (see example
3).
The input contains several test cases. Each test case consists of a line with an integer m (m ≥ 1), the
minimum number of repetitions, followed by a line containing a string s of length between m and 40000,
inclusive. All characters in s are lowercase characters from “a” to “z”. The last test case is denoted by
m = 0 and must not be processed.
Print one line of output for each test case. If there is no solution, output none; otherwise, print two
integers in a line, separated by a space. The first integer denotes the maximum length of a substring
appearing at least m times; the second integer gives the rightmost starting position of this substring.
3 baaaababababbababbab 11 baaaababababbababbab 3 cccccc 0
5 12 none 4 2
Migrated from old NTUJ.
SWERC 2009 pJ
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