LeetCode Weekly Contest 22

531. Lonely Pixel I
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: 3
Explanation: All the three 'B's are black lonely pixels.
Note:
The range of width and height of the input 2D array is [1,500].

func findLonelyPixel(picture [][]byte) int {
        res := 0
        if 0 == len(picture) {
                return res
        }

        countR := make([]int, len(picture))
        countC := make([]int, len(picture[0]))
        for rowi, rowList := range picture {
                for coli, meta := range rowList {
                        if "B" == string(meta) {
                                countR[rowi]++
                                countC[coli]++
                        }
                }
        }

        for rowi, rowList := range picture {
                for coli, meta := range rowList {
                        if "B" == string(meta) {
                                if 1 == countR[rowi] && 1 == countC[coli] {
                                        res++
                                }
                        }
                }
        }

        return res
}