Solution: Valid Triangle Number
Explore how to count valid triangle triplets in an integer array by applying the sort and search pattern. You will understand the triangle inequality, use sorting to simplify validation, and implement a two-pointer approach that enables efficient identification of all valid triangle combinations.
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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]...