import java.util.*;
 
class Main {
    public static void main(String[] args) {
        int[] nums = {1, 3, 5, 8, 2};
        int k = 2;
 
        if (nums == null || nums.length < 2 || k < 0) {
            System.out.println(0);
            return;
        }
        int left = 0;
        int count = 0;
        int n = nums.length;
        Arrays.sort(nums);
        for (int right = 0; right < n; right++) {
            while(nums[right] - nums[left]>k){
                left++;
            }
            count += (right-left);
        }
        System.out.println("count " +count);
    }
}
 

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