Pairs With a Given Difference
Count the pairs of positions i < j with |ai − aj| = K (K ≥ 0).
Input: the first line has N and K; the second line has N integers.
Output: the number of pairs at absolute difference K.
Constraints:
- 1 ≤ N ≤ 105
- 0 ≤ K ≤ 109
- −109 ≤ ai ≤ 109
Sample Tests
Input 1
5 2 1 5 3 4 2
Output 1
3
Input 2
4 0 7 7 7 1
Output 2
3
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