0661. Image Smoother #

class Solution {
    public int conv(int i, int j, int[][] img) {
        int M = img.length, N = img[0].length;
        int numerator = 0, denominator = 0;
        for (int row = i-1; row <= i+1; row++) {
            for (int col = j-1; col <= j+1; col++) {
                if (0 <= row && row < M && 0 <= col && col < N) {
                    numerator += img[row][col];
                    denominator++;
                }
            }
        }
        return numerator / denominator;
    }
    public int[][] imageSmoother(int[][] img) {
        int M = img.length, N = img[0].length;
        int[][] ans = new int[M][N];
        for (int i = 0; i < M; i++) {
            for (int j = 0; j < N; j++) {
                ans[i][j] = conv(i, j, img);
            }
        }
        return ans;
    }
}