Solution: Valid Triangle Number
Explore how to determine the number of valid triangle triplets from an array of integers by applying sorting and the two-pointer search pattern. Understand the triangle inequality principle and learn to implement an efficient solution with time complexity O(n²). Gain skills to identify valid combinations by fixing the largest side and exploring pairs.
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Statement
Given an array of integers, nums, determine the number of triplets of distinct indices (i, j, k) that can be selected from the array such that the values at those indices can form the sides of a valid triangle.
Return this count as the result.
Note: The triplet of indices is treated as an unordered combination, not a permutation. For example, indices (0, 1, 2) and (2, 1, 0) represent the same triplet and should be counted once.
Constraints:
nums.lengthnums[i]...