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题目

The distance of a pair of integers a and b is defined as the absolute difference between a and b.

Given an integer array nums and an integer k, return the kth smallest distance among all the pairs nums[i] and nums[j] where 0 <= i < j < nums.length.

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.

Example 2:

Input: nums = [1,1,1], k = 2
Output: 0

Example 3:

Input: nums = [1,6,1], k = 3
Output: 5

Constraints:

• n == nums.length
• 2 <= n <= 104
• 0 <= nums[i] <= 106
• 1 <= k <= n * (n - 1) / 2

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代码

class Solution {
public:
    int smallestDistancePair(vector<int>& nums, int k) {
        sort(nums.begin(), nums.end());
        int low = 0, high = 100000000;
        while(low < high)
        {
            int mid = (low + high) / 2, count = 0;
            for(int i = 0, j = i+1; i < nums.size(); i++)
            {
                while(j < nums.size() && nums[j] - nums[i] <= mid) j++;
                count += j - i - 1;
            }
            if(count < k)
            {
                low = mid+1;
            }
            else
            {
                high = mid;
            }
        }
        return high;
    }
};
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