Magic Pairs Codechef Solution|Problem Code: ALEXNUMB

Problem

Alexandra has some distinct integer numbers a₁,a₂…a_n. Count number of pairs (i,j) such that:1≤ i ≤ n1≤ j ≤ na_i < a_j

Input

The first line of the input contains an integer T denoting the number of test cases. The description of T test cases follows.The first line of each test case contains a single integer n denoting the number of numbers Alexandra has. The second line contains n space-separated distinct integers a₁, a₂, …, a_n denoting these numbers.

Output

For each test case, output a single line containing number of pairs for corresponding test case.

Constraints

• 1 ≤ T ≤ 4
• 1 ≤ n ≤ 100000
• 0 ≤ a_i ≤ 10⁹
• All the a_i are distinct

Sample Input 1

2
2
2 1
3
3 1 2

Sample Output 1

1
3

Explanation

Case 1: Only one such pair: (2,1)

Case 2: 3 possible pairs: (2,1), (2,3), (3,1)

Magic Pairs – CodeChef Solution in JAVA

import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int T = sc.nextInt();
		for (int tc = 0; tc < T; tc++) {
			int n = sc.nextInt();
			int[] a = new int[n];
			for (int i = 0; i < a.length; i++) {
				a[i] = sc.nextInt();
			}
			System.out.println(solve(a));
		}
		sc.close();
	}
	static long solve(int[] a) {
		return (long) a.length * (a.length - 1) / 2;
	}
}

Disclaimer: The above Problem (Magic Pairs  ) is generated by CodeChef but the solution is provided by  Chase2learn.This tutorial is only for Educational and Learning purpose.