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:
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| 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].
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| class Solution {
public int findLonelyPixel(char[][] picture) {
if (picture == null || picture.length == 0 || picture[0] == null || picture[0].length == 0) {
return 0;
}
Map<Integer, Integer> colMap = new HashMap<>();
Map<Integer, Integer> rowMap = new HashMap<>();
int result = 0;
for (int i = 0; i < picture.length; i++) {
for (int j = 0; j < picture[0].length; j++) {
if (picture[i][j] == 'B') {
colMap.put(j, colMap.getOrDefault(j, 0) + 1);
rowMap.put(i, rowMap.getOrDefault(i, 0) + 1);
}
}
}
for (int i = 0; i < picture.length; i++) {
for (int j = 0; j < picture[0].length; j++) {
if (picture[i][j] == 'B' && colMap.getOrDefault(j, 0) == 1 && rowMap.getOrDefault(i, 0) == 1) {
result++;
}
}
}
return result;
}
}
|