0611. Valid Triangle Number

https://leetcode.com/problems/valid-triangle-number

Description

Given an integer array nums, return the number of triplets chosen from the array that can make triangles if we take them as side lengths of a triangle.

Example 1:

**Input:** nums = [2,2,3,4]
**Output:** 3
**Explanation:** Valid combinations are: 
2,3,4 (using the first 2)
2,3,4 (using the second 2)
2,2,3

Example 2:

**Input:** nums = [4,2,3,4]
**Output:** 4

Constraints:

• 1 <= nums.length <= 1000

• 0 <= nums[i] <= 1000

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