Given an m x n
picture
consisting of black 'B'
and white 'W'
pixels, return the number of black lonely pixels.
A black lonely pixel is a character 'B'
that located at a specific position where the same row and same column don't have any other black pixels.
Example 1:
Input: picture = [["W","W","B"],["W","B","W"],["B","W","W"]] Output: 3 Explanation: All the three 'B's are black lonely pixels.
Example 2:
Input: picture = [["B","B","B"],["B","B","B"],["B","B","B"]] Output: 0
Constraints:
m == picture.length
n == picture[i].length
1 <= m, n <= 500
picture[i][j]
is'W'
or'B'
.