添加python版本三

problems/0200.岛屿数量.深搜版.md

@@ -278,6 +278,40 @@ class Solution:
 
         return result
 ```
+```python 
+# 我们用三个状态去标记每一个格子
+# 0 代表海水
+# 1 代表陆地
+# 2 代表已经访问的陆地
+class Solution:
+    def traversal(self, grid, i, j):
+        m = len(grid)
+        n = len(grid[0])
+
+        if i < 0 or j < 0 or i >= m or j >= n:
+            return   # 越界了
+        elif grid[i][j] == "2" or grid[i][j] == "0":
+            return 
+
+        grid[i][j] = "2"
+        self.traversal(grid, i - 1, j) # 往上走
+        self.traversal(grid, i + 1, j) # 往下走
+        self.traversal(grid, i, j - 1) # 往左走
+        self.traversal(grid, i, j + 1) # 往右走
+
+    def numIslands(self, grid: List[List[str]]) -> int:
+        res = 0
+
+
+        for i in range(len(grid)):
+            for j in range(len(grid[0])):
+                if grid[i][j] == "1":
+                    res += 1
+                    self.traversal(grid, i, j)
+
+        return res
+```
+
 ### JavaScript
 
 ```javascript