solution.cpp

class Solution 
{
public:
    int islandPerimeter(vector<vector<int>>& grid) 
    {
        int result = 0;
        
        for(int i=0;i<grid.size();i++)
        {
            for(int j=0;j<grid[0].size();j++)
            {
                if(grid[i][j] == 1)
                {
                    if( j-1 < 0                 || grid[i][j-1] == 0)
                        result += 1;
                    if( j+1 == grid[0].size()   || grid[i][j+1] == 0)
                        result += 1;
                    if( i-1 < 0                 || grid[i-1][j] == 0)
                        result += 1;
                    if( i+1 == grid.size()      || grid[i+1][j] == 0)
                        result += 1;
                }
            }
        }
        
        return result;
    }
};