C++ 代码

class Solution {
private:
    bool visited[55][55];
    int dx[5] = {-1, 1, 0, 0};
    int dy[5] = {0, 0, -1, 1};
    int res = 0;
    int n, m;
    int area = 0;
public:
    void dfs(int x, int y, vector<vector<int>>& grid)
    {
        for(int i = 0; i < 4; ++i)
        {
            int nx = x + dx[i];
            int ny = y + dy[i];
            if(nx >= 0 && nx < n && ny >= 0 && ny < m && grid[nx][ny] == 1 && !visited[nx][ny])
            {
                visited[nx][ny] = true;
                area += 1;
                dfs(nx, ny, grid);
            }
        }

    }
    int maxAreaOfIsland(vector<vector<int>>& grid) {
        n = grid.size();
        m = grid[0].size();
        for(int i = 0; i < n; ++i)
        {
            for(int j = 0; j < m; ++j)
            {
                if(!visited[i][j] && grid[i][j] == 1)
                {
                    area = 1;
                    visited[i][j] = true;
                    dfs(i, j, grid);
                    res = max(area, res);
                }
            }
        }
        return res;
    }
};
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