2176 - Count Equal and Divisible Pairs in an Array.

Easy

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:

• nums0 == nums6, and 0 \* 6 == 0, which is divisible by 2.

• nums2 == nums3, and 2 \* 3 == 6, which is divisible by 2.

• nums2 == nums4, and 2 \* 4 == 8, which is divisible by 2.

• nums3 == nums4, 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