2025-08-20 10:29:30 +0000 UTC

Number of Unequal Triplets in Array

Code

class Solution:
    def unequalTriplets(self, nums: List[int]) -> int:
        freqs = [0] * 1001
        for num in nums:
            freqs[num] += 1
        res = 0
        left = 0
        right = len(nums)
        for freq in freqs:
            if freq == 0:
                continue
            right -= freq
            res += left * freq * right
            left += freq
        return res