2025-08-19 10:54:21 +0000 UTC

class Solution:
    def arithmeticTriplets(self, nums: List[int], diff: int) -> int:
        freqs = [[] for _ in range(201)]
        for i, num in enumerate(nums):
            freqs[num].append(i)
        length = len(nums)
        res = 0
        for i in range(length):
            num1 = nums[i]
            for j in range(i + 1, length):
                num2 = nums[j]
                if num2 - num1 != diff:
                    continue
                num3 = num2 + diff 
                if num3 > 200:
                    continue
                for k in freqs[num3]:
                    if k > j:
                        res += 1
                        break
        return res