Given a picture consisting of black and white pixels, find the number of black lonely pixels.

The picture is represented by a 2D char array consisting of ‘B‘ and ‘W‘, which means black and white pixels respectively.

A black lonely pixel is character ‘B‘ that located at a specific position where the same row and same column don‘t have any other black pixels.

Example:

Input: [[‘W‘, ‘W‘, ‘B‘], [‘W‘, ‘B‘, ‘W‘], [‘B‘, ‘W‘, ‘W‘]]Output: 3Explanation: All the three ‘B‘s are black lonely pixels.

Note:

1. The range of width and height of the input 2D array is [1,500].

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[LeetCode] Lonely Pixel I 孤独的像素之一