Create average-height-of-buildings-in-each-segment.py

Author: kamyu104

Python/average-height-of-buildings-in-each-segment.py

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+# Time:  O(nlogn)
+# Space: O(n)
+
+class Solution(object):
+    def averageHeightOfBuildings(self, buildings):
+        """
+        :type buildings: List[List[int]]
+        :rtype: List[List[int]]
+        """
+        points = []
+        for x, y, h in buildings:
+            points.append((x, 1, h))
+            points.append((y, -1, h))
+        points.sort()
+        result = []
+        total = cnt = 0
+        prev = -1
+        for curr, c, h in points:
+            if cnt and curr != prev:
+                if result and result[-1][1] == prev and result[-1][2] == total//cnt:
+                    result[-1][1] = curr
+                else:
+                    result.append([prev, curr, total//cnt])
+            total += h*c
+            cnt += c
+            prev = curr
+        return result
+
+
+# Time:  O(nlogn)
+# Space: O(n)
+import collections
+
+
+class Solution2(object):
+    def averageHeightOfBuildings(self, buildings):
+        """
+        :type buildings: List[List[int]]
+        :rtype: List[List[int]]
+        """
+        count = collections.defaultdict(lambda: (0, 0))
+        for x, y, h in buildings:
+            count[x] = (count[x][0]+1, count[x][1]+h)
+            count[y] = (count[y][0]-1, count[y][1]-h)
+        points = sorted(count.iteritems())
+        result = []
+        total = cnt = 0
+        prev = -1
+        for curr, (c, h) in points:
+            if cnt:
+                if result and result[-1][1] == prev and result[-1][2] == total//cnt:
+                    result[-1][1] = curr
+                else:
+                    result.append([prev, curr, total//cnt])
+            total += h
+            cnt += c
+            prev = curr
+        return result