Stack method solved

NeetCodeRoadmap/Stack/84_Largest_Rectangle_in_Histogram.py

@@ -4,37 +4,27 @@ class Solution(object):
         :type heights: List[int]
         :rtype: int
         """
-        rect = []
+        heights.append(0)
-        h = len(heights)
+        stack = [-1]
+        ans = 0
+        for i in range(len(heights)):
+            while heights[i] < heights[stack[-1]]:
+                h = heights[stack.pop()]
+                w = i - stack[-1] - 1
+                ans = max(ans, h * w)
+            stack.append(i)
+        heights.pop()
+        return ans
 
-        if len(heights) <= 2:
-            if len(heights) == 1:
-                return heights[0]
-            else:
-                if heights[0] == 0 or heights[1] == 0:
-                    return max(heights[0], heights[1])
-                low = min(heights[0], heights[1])
-                return low*2
-
-        for x in range(h):
-            count = 1
-            for y in range(x+1, h):
-                if heights[x] == min(heights):
-                    rect.append(heights[x]*len(heights))
-                elif heights[x] > heights[y]:
-                    # print(f'{heights[x]} * {count} = {heights[x]*count}')
-                    rect.append(heights[x]*count)
-                else:
-                    count += 1
-        
-        if rect:
-            return max(rect)
-        else:
-            return 0
 obj = Solution()
 # print(obj.largestRectangleArea([2,1,5,6,2,3])) # 10
 # print(obj.largestRectangleArea([2,4])) # 4
 # print(obj.largestRectangleArea([0,9])) # 9
 # print(obj.largestRectangleArea([0,0,0])) # 0
 # print(obj.largestRectangleArea([2,1,2])) # 3
-print(obj.largestRectangleArea([1,2,2]) # 4
+# print(obj.largestRectangleArea([1,2,2])) # 4
+# print(obj.largestRectangleArea([0,2,0])) # 2
+# print(obj.largestRectangleArea([5,4,1,2])) # 8
+# print(obj.largestRectangleArea([2,0,2])) # 2
+# print(obj.largestRectangleArea([1,2,3,4,5])) # 9
+# print(obj.largestRectangleArea([4,2,0,3,2,5])) # 6

NeetCodeRoadmap/Stack/tempCodeRunnerFile.py

@@ -1,4 +1,10 @@
-print(obj.largestRectangleArea([2,1,5,6,2,3])) # 10
+    stack = [-1]
-print(obj.largestRectangleArea([2,4])) # 4
+        ans = 0
-print(obj.largestRectangleArea([0,9])) # 9
+        for i in xrange(len(height)):
-print(obj.largestRectangleArea([0,0,0])) # 9
+            while height[i] < height[stack[-1]]:
+                h = height[stack.pop()]
+                w = i - stack[-1] - 1
+                ans = max(ans, h * w)
+            stack.append(i)
+        height.pop()
+        return ans