Leetcode: 2475. Number of Unequal Triplets in Array

Can we use brute-force to solve the problem? As \(n \leq 100\), we can go over all triplets in the array and count ones that satisfy the condition. Time complexity is \(O(n^3)\) and space is \(O(n)\).

class Solution:
    def unequalTriplets(self, nums: List[int]) -> int:
        N = len(nums)
        ans = 0
        for i in range(N):
            for j in range(i + 1, N):
                for k in range(j + 1, N):
                    if len(set([nums[i], nums[j], nums[k]])) == 3:
                        ans += 1
        return ans

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Interview preparation: V