[326]Power of Three
2016-08-27 20:28
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【题目描述】
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?
【题目思路】
如果是3的幂必然取以3为底的对数得到的是整数,而stl库里有log的函数,因此只要判断是否以3为底的对数是否为整数即可
【代码】
class Solution {
public:
bool isPowerOfThree(int n) {
double ans=log10(n)/log10(3);
return (ans-int(ans))==0?true:false;
}
};
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?
【题目思路】
如果是3的幂必然取以3为底的对数得到的是整数,而stl库里有log的函数,因此只要判断是否以3为底的对数是否为整数即可
【代码】
class Solution {
public:
bool isPowerOfThree(int n) {
double ans=log10(n)/log10(3);
return (ans-int(ans))==0?true:false;
}
};
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