Power of Three

07/18/2016 Math

Question

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?

Solution

Result: Accepted Time: 164 ms

Here should be some explanations.

class ThreeSet{
    set<int> st;
public:
    ThreeSet(){
        int i = 1;
        while(i >0)
        {
            st.insert(i);
            i*=3;
        }
    }
    int count(int n)
    {
        return st.count(n);
    }
};

class Solution {
   static ThreeSet st;
    
public:
    
    bool isPowerOfThree(int n) {
        return st.count(n);
    }
};

ThreeSet Solution::st;

Complexity Analytics

  • Time Complexity:
  • Space Complexity: