1 public class Solution {
2 public int islandPerimeter(int[][] grid) {
3 int ans = 0;
4 for (int i = 0; i < grid.length; i++) {
5 for (int j = 0; j < grid[0].length; j++) {
6 if (grid[i][j] == 1) {
7 if (i == 0 || (i > 0 && grid[i-1][j] == 0)) ans++; //top
8 if (i == grid.length-1 || (i < grid.length-1 && grid[i+1][j] == 0)) ans++; //bottom
9 if (j == 0 || (j > 0 && grid[i][j-1] == 0)) ans++; //left
10 if (j == grid[0].length-1 || (j < grid[0].length-1 && grid[i][j+1] == 0)) ans++; //right
11 }
12 }
13 }
14 return ans;
15 }
16 }