Given a 2D integer matrix M representing the gray scale of an image, you need to design a smoother to make the gray scale of each cell becomes the average gray scale (rounding down) of all the 8 surrounding cells and itself. If a cell has less than 8 surrounding cells, then use as many as you can.
Example 1:
Input: [[1,1,1], [1,0,1], [1,1,1]] Output: [[0, 0, 0], [0, 0, 0], [0, 0, 0]] Explanation: For the point (0,0), (0,2), (2,0), (2,2): floor(3/4) = floor(0.75) = 0 For the point (0,1), (1,0), (1,2), (2,1): floor(5/6) = floor(0.83333333) = 0 For the point (1,1): floor(8/9) = floor(0.88888889) = 0
Note:
Intuition and Algorithm
For each cell in the grid, look at the immediate neighbors - up to 9 of them, including the original cell.
Then, we will add the sum of the neighbors into ans[r][c] while recording count, the number of such neighbors. The final answer is the sum divided by the count.
Complexity Analysis
Time Complexity: , where is the number of pixels in our image. We iterate over every pixel.
Space Complexity: , the size of our answer.
Analysis written by: @awice.