leetcode200

深度优先搜索，每次遇到1，则岛的数量+1，从这个1开始找到所有相连的1，将其改为0。

public class Solution
    {
        private void dfsSearch(char[,] grid, int i, int j, int rows, int cols)
        {
            if (i < 0 || i >= rows || j < 0 || j >= cols)
            {
                return;
            }
            if (grid[i, j] == '0')
            {
                return;
            }
            grid[i, j] = '0';
            dfsSearch(grid, i + 1, j, rows, cols);
            dfsSearch(grid, i - 1, j, rows, cols);
            dfsSearch(grid, i, j + 1, rows, cols);
            dfsSearch(grid, i, j - 1, rows, cols);
        }

        public int NumIslands(char[,] grid)
        {
            var rows = grid.GetLength(0);
            var cols = grid.GetLength(1);
            if (rows == 0 || cols == 0)
            {
                return 0;
            }

            int count = 0;
            for (int i = 0; i < rows; i++)
            {
                for (int j = 0; j < cols; j++)
                {
                    if (grid[i, j] == '1')
                    {
                        count++;
                        dfsSearch(grid, i, j, rows, cols);
                    }
                }
            }
            return count;
        }
    }