leetcode 719. Find K-th Smallest Pair Distance c++

Given an integer array, return the k-th smallest distance among all the pairs. The distance of a pair (A, B) is defined as the absolute difference between A and B.

Example 1:

Input:
nums = [1,3,1]
k = 1
Output: 0 
Explanation:
Here are all the pairs:
(1,3) -> 2
(1,1) -> 0
(3,1) -> 2
Then the 1st smallest distance pair is (1,1), and its distance is 0.

 

Note:

1. 2 <= len(nums) <= 10000.
2. 0 <= nums[i] < 1000000.
3. 1 <= k <= len(nums) * (len(nums) - 1) / 2.

class Solution {
public:
    int smallestDistancePair(vector& nums, int k) 
    {
        int len = nums.size();
        sort(nums.begin(),nums.end());
        int left = 0;
        int right = nums[len-1]-nums[0];
        int mid=0;
        while(leftmid) lowl++;
                count += upl - lowl;
            }
            if(count