题解 | #岛屿数量#

class Solution {
public:
    int m,n;
    int dx[4] = {0,0,1,-1};
    int dy[4] = {1,-1,0,0};
    bool vis[201][201] = { false };

    int solve(vector<vector<char> >& grid)
    {
        m = grid.size();
        n = grid[0].size();

        int count = 0;
        for(int i = 0;i < m;i++)
        {
            for(int j = 0;j < n;j++)
            {
                if(grid[i][j] == '1' && !vis[i][j])
                {
                    count++;
                    dfs(grid,i,j);
                }
            }
        }
        return count;
    }

    void dfs(vector<vector<char> >& grid, int i,int j)
    {
        vis[i][j] = true;
        for(int k = 0;k < 4;k++)
        {
            int x = i + dx[k];
            int y = j + dy[k];
            if(x >= 0 && x < m && y >= 0 && y < n && grid[x][y] == '1' && !vis[x][y])
                dfs(grid,x,y);
        }
    }
};