PERMUT2 - Ambiguous Permutations
Some programming contest problems are really tricky: not only do they
require a different output format from what you might have expected, but
also the sample output does not show the difference. For an example,
let us look at permutations.
A permutation of the integers 1 to n is an ordering of these integers. So the natural way to represent a permutation is to list the integers in this order. With n = 5, a permutation might look like 2, 3, 4, 5, 1.
However, there is another possibility of representing a permutation: You create a list of numbers where the i-th number is the position of the integer i in the permutation. Let us call this second possibility an inverse permutation. The inverse permutation for the sequence above is 5, 1, 2, 3, 4.
An ambiguous permutation is a permutation which cannot be distinguished from its inverse permutation. The permutation 1, 4, 3, 2 for example is ambiguous, because its inverse permutation is the same. To get rid of such annoying sample test cases, you have to write a program which detects if a given permutation is ambiguous or not.
The input contains several test cases.
The first line of each test case contains an integer n (1 ≤ n ≤ 100000). Then a permutation of the integers 1 to n follows in the next line. There is exactly one space character between consecutive integers. You can assume that every integer between 1 and n appears exactly once in the permutation.
The last test case is followed by a zero.
For each test case output whether the permutation is ambiguous or not. Adhere to the format shown in the sample output.
4 1 4 3 2 5 2 3 4 5 1 1 1 0
ambiguous not ambiguous ambiguous
|Added by:||Adrian Kuegel|
|Cluster:||Cube (Intel Pentium G860 3GHz)|
|Languages:||All except: NODEJS PERL 6 SCM chicken VB.net|
|Resource:||own problem, used in University of Ulm Local Contest 2005|
Thanks @Adrian Kuegel.
@gulbarga master check whether ur writing ambiguous and not ambiguous properly....cost me 1 wa. :)
can i pls have some additional test cases for this ? The ones given, work for me and yet i get a WA.
good question :D
"You create a list of numbers where the i-th number is the position of the integer i in the permutation."
can anybody please help me understand how 51234 is the inverse permutation of 23451 ???