2006. Count Number of Pairs With Absolute Difference K

Given an integer array nums and an integer k, return the number of pairs (i, j) where i < j such that |nums[i] - nums[j]| == k.

The value of |x| is defined as:

  • x if x >= 0.
  • -x if x < 0.

 

Example 1:

Input: nums = [1,2,2,1], k = 1
Output: 4
Explanation: The pairs with an absolute difference of 1 are:
- [1,2,2,1]
- [1,2,2,1]
- [1,2,2,1]
- [1,2,2,1]

Example 2:

Input: nums = [1,3], k = 3
Output: 0
Explanation: There are no pairs with an absolute difference of 3.

Example 3:

Input: nums = [3,2,1,5,4], k = 2
Output: 3
Explanation: The pairs with an absolute difference of 2 are:
- [3,2,1,5,4]
- [3,2,1,5,4]
- [3,2,1,5,4]

 

Constraints:

  • 1 <= nums.length <= 200
  • 1 <= nums[i] <= 100
  • 1 <= k <= 99

2006. Count Number of Pairs With Absolute Difference K
struct Solution;

impl Solution {
    fn count_k_difference(nums: Vec<i32>, k: i32) -> i32 {
        let n = nums.len();
        let mut res = 0;
        for i in 0..n {
            for j in i + 1..n {
                if (nums[j] - nums[i]).abs() == k {
                    res += 1;
                }
            }
        }
        res
    }
}

#[test]
fn test() {
    let nums = vec![1, 2, 2, 1];
    let k = 1;
    let res = 4;
    assert_eq!(Solution::count_k_difference(nums, k), res);
    let nums = vec![1, 3];
    let k = 3;
    let res = 0;
    assert_eq!(Solution::count_k_difference(nums, k), res);
    let nums = vec![3, 2, 1, 5, 4];
    let k = 2;
    let res = 3;
    assert_eq!(Solution::count_k_difference(nums, k), res);
}