class Solution {
public int islandPerimeter(int[][] grid) {
int islands = 0;
int neighbors = 0;
for (int i = 0; i < grid.length; i++) {
for (int j = 0; j < grid[i].length; j++) {
if (grid[i][j] == 0) continue;
islands++;
if (i < grid.length - 1 && grid[i + 1][j] == 1) neighbors++;
if (j < grid[i].length - 1 && grid[i][j + 1] == 1) neighbors++;
}
}
return islands * 4 - neighbors * 2;
}
}