Inverse List

2.6

41 votes
Ad-Hoc, Easy, Implementation
Problem

There are many ways to order a list of integers from 1 to n. For example, if n=3, the list could be : [312].

But there is a special way to create another list from the given list of integers. In this list, position of integer i is the ith number in the given list. So following this rule, the given list will be written as: [231]. This list is called inverse list. Now there exists some list whose inverse list is identical. For example, inverse list of [123] is same as given list. Given a list of integers you have to determine whether the list is inverse or not.

The input contains several test cases. The first line is the number of test cases t (1<=t<=100) . The first line of each test case contains an integer n(1<=n<=100000). Then a list of the integers 1 to n follows in the next line.

Time Limit: 2
Memory Limit: 256
Source Limit:
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