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-rw-r--r--check_num_sum_pow3.c26
-rw-r--r--check_num_sum_pow3.py29
2 files changed, 55 insertions, 0 deletions
diff --git a/check_num_sum_pow3.c b/check_num_sum_pow3.c
new file mode 100644
index 0000000..67fe299
--- /dev/null
+++ b/check_num_sum_pow3.c
@@ -0,0 +1,26 @@
+// 1780. Check if Number is a Sum of Powers of Three
+#include "leetcode.h"
+
+/*
+ * 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'
+ */
+
+bool checkPowersOfThree(int n) {
+ static int pow3[] = {4782969, 1594323, 531441, 177147, 59049,
+ 19683, 6561, 2187, 729, 243,
+ 81, 27, 9, 3, 1};
+ for (int i = 0; i < 15; i++)
+ if (n >= 2 * pow3[i])
+ return false;
+ else if (n >= pow3[i])
+ n -= pow3[i];
+ return true;
+}
+
+int main() {
+ printf("%d\n", checkPowersOfThree(12)); // expect: 1
+ printf("%d\n", checkPowersOfThree(91)); // expect: 1
+ printf("%d\n", checkPowersOfThree(21)); // expect: 0
+}
diff --git a/check_num_sum_pow3.py b/check_num_sum_pow3.py
new file mode 100644
index 0000000..b931e50
--- /dev/null
+++ b/check_num_sum_pow3.py
@@ -0,0 +1,29 @@
+# 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))