Right Triangles

You are given a 2D boolean matrix grid.

Return an integer that is the number of right triangles that can be made with the 3 elements of grid such that all of them have a value of 1.

Note:

• A collection of 3 elements of grid is a right triangle if one of its elements is in the same row with another element and in the same column with the third element. The 3 elements do not have to be next to each other.

Example 1:

010011010010011010

Input: grid = [[0,1,0],[0,1,1],[0,1,0]]

Output: 2

Explanation:

There are two right triangles.

Example 2:

100001011000

Input: grid = [[1,0,0,0],[0,1,0,1],[1,0,0,0]]

Output: 0

Explanation:

There are no right triangles.

Example 3:

101100100101100100

Input: grid = [[1,0,1],[1,0,0],[1,0,0]]

Output: 2

Explanation:

There are two right triangles.

Constraints:

• 1 <= grid.length <= 1000
• 1 <= grid[i].length <= 1000
• 0 <= grid[i][j] <= 1