def countKDifference(self, nums: List[int], k: int) -> int: ''' res, n = 0, len(nums) for i in range(n): for j in range(i+1, n): if abs(nums[i]-nums[j]) == k: res += 1 return res ''' res, d = 0, defaultdict(int) for i in nums: d[k+i] += 1 for ...