public int islandPerimeter(int[][] grid) {

int perimeter = 0;

if(grid == null || grid.length == 0) {

return perimeter;

}

for(int i = 0; i < grid.length; i++) {

for(int j = 0; j < grid[i].length; j++) {

if(grid[i][j] == 1) {

perimeter += numNeighbors(grid, i, j);

return perimeter;

}

}

}

return perimeter;

}

public int numNeighbors(int[][] grid, int x, int y) {

if(x < 0 || x >= grid.length || y < 0 || y >= grid[x].length || grid[x][y] == 0) {

return 1;

}

if(grid[x][y] == -1) {

return 0;

}

grid[x][y] = -1;

return numNeighbors(grid, x + 1, y) +

numNeighbors(grid, x - 1, y) +

numNeighbors(grid, x, y + 1) +

numNeighbors(grid, x, y - 1);

}