1582 Special Positions in a Binary Matrix

Given an `m x n` binary matrix `mat`, return the number of special positions in `mat`.

A position `(i, j)` is called special if `mat[i][j] == 1` and all other elements in row `i` and column `j` are `0` (rows and columns are 0-indexed).

Example 1:

``````1 0 0
0 0[1]
1 0 0

Input: mat = [[1,0,0],[0,0,1],[1,0,0]]
Output: 1
Explanation: (1, 2) is a special position because mat[1][2] == 1
and all other elements in row 1 and column 2 are 0.
``````

Example 2:

``````[1]0 0
0[1]0
0 0[1]

Input: mat = [[1,0,0],[0,1,0],[0,0,1]]
Output: 3
Explanation: (0, 0), (1, 1) and (2, 2) are special positions.
``````

Constraints:

• `m == mat.length`
• `n == mat[i].length`
• `1 <= m, n <= 100`
• `mat[i][j]` is either `0` or `1`.
 `````` 1 2 3 4 5 6 7 8 9 10 `````` ``````class Solution: def numSpecial(self, mat: List[List[int]]) -> int: row_sums = [sum(r) for r in mat] col_sums = [sum([r[i] for r in mat]) for i in range(len(mat[0]))] res = 0 for i in range(len(mat)): for j in range(len(mat[0])): if mat[i][j] == 1 and row_sums[i] == 1 and col_sums[j] == 1: res += 1 return res``````