Merge pull request #2 from gantavya12/patch-2

Create The-Skyline-Problem.py

Author: gantavyamalviya

Python/The-Skyline-Problem.py

@@ -0,0 +1,22 @@
+class Solution:
+    def getSkyline(self, buildings):
+        points  = [(l,h,-1,i) for i, (l,r,h) in enumerate(buildings)]
+        points += [(r,h,1,i) for i, (l,r,h) in enumerate(buildings)]
+        points.sort(key = lambda x: (x[0], x[1]*x[2]))
+        heap, active, ans = [(0,-1)], set([-1]), []
+        
+        for x, h, lr, ind in points:
+            if lr == -1: active.add(ind)
+            else: active.remove(ind)
+           
+            if lr == -1:
+                if h > -heap[0][0]: 
+                    ans.append([x, h])
+                heappush(heap, (-h, ind))
+            else:
+                if h == -heap[0][0]:   
+                    while heap and heap[0][1] not in active: heappop(heap)
+                if -heap[0][0] != ans[-1][1]: 
+                    ans.append([x, -heap[0][0]])
+                
+        return ans