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(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(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.