差的绝对值为 K 的数对数目

/**
 * Approach: We use Java Streams to iterate through the array and count the pairs 
 * satisfying the condition using IntStream and filter.
 *
 * Time Complexity: O(n^2) where n is the number of elements in nums.
 * Space Complexity: O(1) as we are not using any additional space.
 */
import java.util.stream.IntStream;

public class Solution {
    public int countKDifference(int[] nums, int k) {
        return (int) IntStream.range(0, nums.length)
            .flatMap(i -> IntStream.range(i + 1, nums.length)
                .filter(j -> Math.abs(nums[i] - nums[j]) == k))
            .count();
    }
}