463-Island-Perimeter.cpp

class Solution {
public:
    
int islandPerimeter(std::vector<std::vector<int>>& grid) {
    int perimeter = 0;
    int rows = grid.size();
    int cols = grid[0].size();
    
    for (int i = 0; i < rows; ++i) {
        for (int j = 0; j < cols; ++j) {
            if (grid[i][j] == 1) {
                perimeter += 4;
                
               
                if (i > 0 && grid[i - 1][j] == 1) {
                    perimeter -= 2;
                }
                if (j > 0 && grid[i][j - 1] == 1) {
                    perimeter -= 2;
                }
            }
        }
    }
    
    return perimeter;
}

};