leetcode 200. Number of Islands | 200. 岛屿数量（Java）

深碍√TFBOYSˉ_ 2022-10-05 05:46 133阅读 0赞

## 题目 ##

[https://leetcode-cn.com/problems/number-of-islands/][https_leetcode-cn.com_problems_number-of-islands]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_16_color_FFFFFF_t_70]

## 题解 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_1_color_FFFFFF_t_70]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_1_color_FFFFFF_t_70 1]

class Solution { 
        public int numIslands(char[][] grid) { 
            int count = 0;
            for (int i = 0; i < grid.length; i++) { 
                for (int j = 0; j < grid[0].length; j++) { 
                    if (grid[i][j] == '1') { 
                        count++;
                        infect(grid, i, j);
                    }
                }
            }
            return count;
        }
    
        public void infect(char[][] grid, int x, int y) { 
            if (x >= grid.length || x < 0 || y >= grid[0].length || y < 0 || grid[x][y] != '1') return;
            grid[x][y] = '2';
            infect(grid, x - 1, y);
            infect(grid, x + 1, y);
            infect(grid, x, y - 1);
            infect(grid, x, y + 1);
        }
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_16_color_FFFFFF_t_70 1]

[https_leetcode-cn.com_problems_number-of-islands]: https://leetcode-cn.com/problems/number-of-islands/
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_16_color_FFFFFF_t_70]: /images/20221005/324a366bf5194ee3bb0234143874c6f1.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_1_color_FFFFFF_t_70]: /images/20221005/df3236f21cc74d739db5b15a6e762e54.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_1_color_FFFFFF_t_70 1]: /images/20221005/56f4f2c50ef74e4eb0adb57428ce8714.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_16_color_FFFFFF_t_70 1]: /images/20221005/3d71478f113f40a6b9baed7fcddf5560.png