count-equal-and-divisible-pairs-in-an-array.cpp

//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[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


//solution//

class Solution {
public:
    int countPairs(vector<int>& nums, int k) {
     int count = 0;
     for(int i=0;i<nums.size();i++){
         for(int j=i+1;j<nums.size();j++){
             if(nums[i]==nums[j] && (i*j)%k==0){
                 count++;
             }
         }
     }   
     return count;
    }
};