problem2176.java

/**

Given a 0-indexed integer array nums of length n and an integer k, return the number 
of pairs (i, j) where 0 <= i < j < n, such that nums[i] == nums[j] and (i * j) is 
divisible by k.
 

Example 1:

Input: nums = [3,1,2,2,2,1,3], k = 2
Output: 4
Explanation:
There are 4 pairs that meet all the requirements:
- nums[0] == nums[6], and 0 * 6 == 0, which is divisible by 2.
- nums[2] == nums[3], and 2 * 3 == 6, which is divisible by 2.
- nums[2] == nums[4], and 2 * 4 == 8, which is divisible by 2.
- nums[3] == nums[4], and 3 * 4 == 12, which is divisible by 2.
Example 2:

Input: nums = [1,2,3,4], k = 1
Output: 0
Explanation: Since no value in nums is repeated, there are no pairs (i,j) that meet 
all the requirements.
 

Constraints:

1 <= nums.length <= 100
1 <= nums[i], k <= 100
 */


/****************************************************************************
             2176. Count Equal and Divisible Pairs in an Array
****************************************************************************/

public class problem2176 {
    public static void main(String[] args) {
        int[] nums = {3,1,2,2,2,1,3};
        int k = 2;
        int count = 0;

        for(int i=0; i<nums.length; i++) {
            for(int j=i+1; j<nums.length; j++) {
                if(nums[i] == nums[j] && ((i*j)%k) == 0) {
                    count++;
                }
            }
        }
        System.out.println("count  = " + count);    // return count;
    }
}