Counting Triangles

Problem Description

You are given an array of N non-negative integers, A₀, A₁,..., A_N-1.
Considering each array element A_i as the edge length of some line segment, count the number of triangles that you can form using these array values.

Notes:

You can use any value only once while forming each triangle. The order of choosing the edge lengths doesn't matter. Any triangle formed should have a positive area.
Return answer modulo 10⁹ + 7.

Problem Constraints

1 <= |A| <= 10³
0 <= A_i <= 10⁶

Input Format

The first argument is an integer array A.

Output Format

Return an integer equal to the count of the number of triangles that you can form.

Example Input

A = [1, 1, 1, 2, 2]

Example Output

NOTE: You only need to implement the given function. Do not read input, instead use the arguments to the function. Do not print the output, instead return values as specified. Still have a question? Checkout Sample Codes for more details.

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Counting Triangles

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