LeetCode 463. 島嶼的周長(看懂題意就好)

島嶼的周長

const int dx[] = {-1,0,1,0};
const int dy[] = {0,1,0,-1};
class Solution {
public:
    int islandPerimeter(vector<vector<int>>& grid) {
        int ans = 0;
        for(int i=0;i<grid.size();i++){
            for(int j=0;j<grid[0].size();j++){
                if(!grid[i][j]){
                    continue;   
                }
                ans+=4;
                for(int k=0;k<4;k++){
                    int x = i+dx[k];
                    int y = j+dy[k];
                    if(x>=0&&x<grid.size()&&y>=0 &&y<grid[0].size() ){
                        if(grid[x][y]){
                            ans--;
                        }
                    }
                }
            }
        }
        return ans;
    }
};