2176. Count Equal and Divisible Pairs in an Array

#### QUESTION:

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 == nums, and 0 * 6 == 0, which is divisible by 2.
- nums == nums, and 2 * 3 == 6, which is divisible by 2.
- nums == nums, and 2 * 4 == 8, which is divisible by 2.
- nums == nums, 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
``````

#### EXPLANATION:

easy的题目, 也就是两个for循环再加上一个判断就是可以了.

#### SOLUTION:

``````class Solution {
func countPairs(_ nums: [Int], _ k: Int) -> Int {
var result:Int = 0
for indexI in 0..<nums.count {
for indexJ in indexI+1..<nums.count {
if ((nums[indexI] == nums[indexJ])
&& (indexI*indexJ)%k == 0) {
result+=1
}
}
}
return result
}
}
``````
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