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
ifx >= 0
. -
-x
ifx < 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
SOLUTION:
class Solution:
def countKDifference(self, nums: List[int], k: int) -> int:
exists = {}
ctr = 0
for i, num in enumerate(nums):
exists[num] = exists.get(num, []) + [i]
for i, num in enumerate(nums):
for val in [num - k, num + k]:
if val in exists:
for j in exists[val]:
if j > i:
ctr += 1
return ctr
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