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-rw-r--r--check_num_sum_pow3.py29
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diff --git a/check_num_sum_pow3.py b/check_num_sum_pow3.py
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+# 1780. Check if Number is a Sum of Powers of Three
+
+"""
+given an integer 'n', return true if it is possible to represent 'n' as the
+sum of distinct powers of three. otherwise, return false. an integer 'y' is a
+power of three if there exists an integer 'x' such that 'y == 3^x'
+"""
+
+
+class Solution(object):
+ def checkPowersOfThree(self, n):
+ """
+ :type n: int
+ :rtype: bool
+ """
+ pow3 = [3**i for i in reversed(range(15))]
+ for i in pow3:
+ if n >= 2 * i:
+ return False
+ elif n >= i:
+ n -= i
+ return True
+
+
+if __name__ == "__main__":
+ obj = Solution()
+ print(obj.checkPowersOfThree(12))
+ print(obj.checkPowersOfThree(91))
+ print(obj.checkPowersOfThree(21))