Update maximal-rectangle.py

Author: kamyu104

Python/maximal-rectangle.py

@@ -8,29 +8,21 @@ def maximalRectangle(self, matrix):
         :rtype: int
         """
         def largestRectangleArea(heights):
-            increasing, area, i = [], 0, 0
-            while i <= len(heights):
-                if not increasing or (i < len(heights) and heights[i] > heights[increasing[-1]]):
-                    increasing.append(i)
-                    i += 1
-                else:
-                    last = increasing.pop()
-                    if not increasing:
-                        area = max(area, heights[last] * i)
-                    else:
-                        area = max(area, heights[last] * (i - increasing[-1] - 1 ))
-            return area
+            stk, result, i = [-1], 0, 0
+            for i in xrange(len(heights)+1):
+                while stk[-1] != -1 and (i == len(heights) or heights[stk[-1]] >= heights[i]):
+                    result = max(result, heights[stk.pop()]*((i-1)-stk[-1]))
+                stk.append(i) 
+            return result
 
         if not matrix:
             return 0
-
         result = 0
-        heights = [0] * len(matrix[0])
+        heights = [0]*len(matrix[0])
         for i in xrange(len(matrix)):
             for j in xrange(len(matrix[0])):
                 heights[j] = heights[j] + 1 if matrix[i][j] == '1' else 0
             result = max(result, largestRectangleArea(heights))
-
         return result