Create find-original-array-from-doubled-array.py

Author: kamyu104

Python/find-original-array-from-doubled-array.py

@@ -0,0 +1,17 @@
+# Time:  O(n + klogk), k is the distinct number of changed
+# Space: O(k)
+
+class Solution(object):
+    def findOriginalArray(self, changed):
+        """
+        :type changed: List[int]
+        :rtype: List[int]
+        """
+        if len(changed)%2:
+            return []
+        cnts = collections.Counter(changed)
+        for x in sorted(cnts.iterkeys()):
+            if cnts[x] > cnts[2*x]:
+                return []
+            cnts[2*x] -= cnts[x] if x else cnts[x]//2
+        return list(cnts.elements())