Inverse List

There are many ways to order a list of integers from 1 to n. For example, if n = 3, the list could be :
 [3 1 2].
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 i-th number in the given list. So following this rule, the given list will be written as:
 [2 3 1].

This list is called inverse list. Now there exists some list whose inverse list is identical. For example, inverse list of [1 2 3] 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.

---

Sample Input

2
3
3 1 2
3
1 2 3

Sample Output

not inverse
inverse

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Time Limit: 2 sec(s) for all input files combined.

Memory Limit: 256 MB

Source Limit: 1024 KB 

 

Code:

 

/*
 * uncomment this if you want to read input.
import java.io.BufferedReader;
import java.io.InputStreamReader;
*/

import java.util.Arrays;
import java.util.Scanner;

public class TestClass {
    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);
        int N = in.nextInt();
        in.nextLine();
        StringBuilder sb = new StringBuilder();

        while (N > 0) {
            N--;
            int T = in.nextInt();
            int a[] = new int[T+1];
            int b[] = new int[T+1];

            for (int i = 1; i <= T; i++) {
                a[i] = in.nextInt();
                b[a[i]] = i;
            }

            if (Arrays.equals(a, b))
                sb.append("inverse\n");
            else
                sb.append("not inverse\n");
        }
        System.out.println(sb);
    }

}