class Solution {
    private int m;
    private int n;

    public int islandPerimeter(int[][] grid) {
        m = grid.length;
        n = grid[0].length;
        int perimeter = 0;

        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if (grid[i][j] == 1) {
                    perimeter += getPerimeter(i, j, grid);
                }
            }
        }
        return perimeter;
    }

    private int getPerimeter(int i, int j, int[][] grid) {
        int perimeter = 0;
        if (i == 0 || grid[i-1][j] == 0) {
            perimeter++;
        }
        if (j == 0 || grid[i][j-1] == 0) {
            perimeter++;
        }
        if (i == m-1 || grid[i+1][j] == 0) {
            perimeter++;
        }
        if (j == n-1 || grid[i][j+1] == 0) {
            perimeter++;
        }
        return perimeter;
    }
}