Create count-sub-islands.py

Author: kamyu104

Python/count-sub-islands.py

@@ -0,0 +1,23 @@
+# Time:  O(m * n)
+# Space: O(1)
+
+class Solution(object):
+    def countSubIslands(self, grid1, grid2):
+        """
+        :type grid1: List[List[int]]
+        :type grid2: List[List[int]]
+        :rtype: int
+        """
+        directions = [(0, 1), (1, 0), (0, -1), (-1, 0)]
+        def dfs(grid1, grid2, i, j):
+            if not (0 <= i < len(grid2) and
+                    0 <= j < len(grid2[0]) and
+                    grid2[i][j] == 1):
+                return 1
+            grid2[i][j] = 0
+            result = grid1[i][j]
+            for di, dj in directions:
+                result &= dfs(grid1, grid2, i+di, j+dj)
+            return result
+            
+        return sum(dfs(grid1, grid2, i, j) for i in xrange(len(grid2)) for j in xrange(len(grid2[0])) if grid2[i][j])