diff options
Diffstat (limited to 'check_num_sum_pow3.c')
-rw-r--r-- | check_num_sum_pow3.c | 26 |
1 files changed, 26 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 +} |