[leetcode] Number of Islands

class Solution
{
private:
  void dfs(vector<vector<char> > &grid, int x, int y)
  {
    if(x < 0 || x >= grid.size()) return;
    if(y < 0 || y >= grid[0].size()) return;
    if(grid[x][y] != ‘1‘) return;

    grid[x][y] = ‘x‘;
    dfs(grid, x-1, y);
    dfs(grid, x+1, y);
    dfs(grid, x, y-1);
    dfs(grid, x, y+1);
  }
public:
  int numIslands(vector<vector<char> > &grid)
  {
    if(grid.empty() || grid[0].empty()) return 0;
    int X = grid.size(), Y = grid[0].size();
    int count = 0;

    for(int i=0; i<X; i++)
    {
      for(int j=0; j<Y; j++)
      {
        if(grid[i][j] == ‘1‘)
        {
          count++;
          dfs(grid, i, j);
        }
      }
    }

    return count;
  }
};