Power of Three
Given an integer, write a function to determine if it is a power of three.
Follow up:
Could you do it without using any loop / recursion?
1 /************************************************************************* 2 > File Name: LeetCode326.c 3 > Author: Juntaran 4 > Mail: Jacinthmail@gmail.com 5 > Created Time: 2016年05月10日 星期二 02时42分09秒 6 ************************************************************************/ 7 8 /************************************************************************* 9 10 Power of Three 11 12 Given an integer, write a function to determine if it is a power of three. 13 14 Follow up: 15 Could you do it without using any loop / recursion? 16 17 ************************************************************************/ 18 19 #include "stdio.h" 20 21 int isPowerOfThree(int n) { 22 double tmp = log10(n)/log10(3); 23 return tmp == (int)tmp ? 1 : 0; 24 } 25 26 int main() 27 { 28 int n = 9; 29 int ret = isPowerOfThree(n); 30 printf("%d ",ret); 31 32 n = 10; 33 ret = isPowerOfThree(n); 34 printf("%d ",ret); 35 36 return 0; 37 }