LeetCode - 326. Power of Three

topic

LeetCode - 326. Power of Three

Topic Link

https://leetcode.com/problems/power-of-three/

Reference blog

Problem-solving ideas

Solution twenty-one start intend to use $ 3 ^ {log_3N} == N $, determines whether a power of 3, is utilized after rounding to the end, and then restored. However, pow arithmetic, floating point arithmetic, and log time, there will be loss of precision. C language number is the log base e, serious loss of precision when calculating the recommended number of base 10 to log10.

Problem-solving Source

1. A Solution

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class { public: bool isPowerOfThree(int大专栏  LeetCode - 326. Power of Threepan> n) { long long int a = 1; while(a < n){ a *= 3; } return a == n; } };

2. Solution two

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class { public: bool isPowerOfThree(int n) { return (n > 0 && log10(n)/log10(3) == int(log10(n)/log10(3))); } };