Create number-of-closed-islands.py

Author: kamyu104

Python/number-of-closed-islands.py

@@ -0,0 +1,32 @@
+# Time:  O(m * n)
+# Space: O(1)
+
+class Solution(object):
+    def closedIsland(self, grid):
+        """
+        :type grid: List[List[int]]
+        :rtype: int
+        """
+        directions = [(0, 1), (1, 0), (0, -1), (-1, 0)]
+        def fill(grid, i, j):
+            if not (0 <= i < len(grid) and 
+                    0 <= j < len(grid[0]) and 
+                    grid[i][j] == 0):
+                return False
+            grid[i][j] = 1
+            for dx, dy in directions:
+                fill(grid, i+dx, j+dy)
+            return True
+
+        for j in xrange(len(grid[0])):
+            fill(grid, 0, j)
+            fill(grid, len(grid)-1, j)
+        for i in xrange(1, len(grid)):
+            fill(grid, i, 0)
+            fill(grid, i, len(grid[0])-1)
+        result = 0
+        for i in xrange(1, len(grid)-1):
+            for j in xrange(1, len(grid[0])-1):
+                if fill(grid, i, j):
+                    result += 1
+        return result