#2367
Number of Arithmetic Triplets
newbie · 120 · lc easy +12 · verified · 85.4% accepted · 1,386 likes · top 97%
Description
You are given a 0-indexed strictly increasing integer array nums and a positive integer diff. An index triple (i, j, k) forms an arithmetic triplet when all three conditions hold:
- i < j < k,
- nums[j] - nums[i] == diff, and
- nums[k] - nums[j] == diff.
Return the count of distinct arithmetic triplets.
Example 1:
Input: nums = [0,1,4,6,7,10], diff = 3
Output: 2
Explanation:
(1, 2, 4) is an arithmetic triplet because both 7 - 4 == 3 and 4 - 1 == 3.
(2, 4, 5) is an arithmetic triplet because both 10 - 7 == 3 and 7 - 4 == 3.
Example 2:
Input: nums = [4,5,6,7,8,9], diff = 2
Output: 2
Explanation:
(0, 2, 4) is an arithmetic triplet because both 8 - 6 == 2 and 6 - 4 == 2.
(1, 3, 5) is an arithmetic triplet because both 9 - 7 == 2 and 7 - 5 == 2.
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