Solved
Easy
Topics
Companies
Given an integer n, return true if it is a power of three. Otherwise, return false.An integer n is a power of three, if there exists an integer x such that n == 3x.
Example 1:
Input: n = 27
Output: true
Explanation: 27 = 33
Example 2:
Input: n = 0
Output: false
Explanation: There is no x where 3x = 0.
Example 3:
Input: n = -1
Output: false
Explanation: There is no x where 3x = (-1).
Constraints:
-231 <= n <= 231–1
Follow up: Could you solve it without loops/recursion?
class Solution {
public boolean isPowerOfThree1(int n) {
int m=1;
while(m<n){
m*=3;
}
return n==m ? true:false;
}
public boolean isPowerOfThree2(int n) {
return rec(n,1);
}
public boolean rec(int n, int m){
if(n==m) return true;
if(m<n) return rec(n, m*3);
return false;
}
/**the largest number divisible by three is 1162261467 before 2^31 -1 , checking it is divisible by it
would be sufficient */
public boolean isPowerOfThree(int n) {
return n > 0 && 1162261467 % n == 0;
}
}
/**
326. Power of Three
Solved
Easy
Topics
Companies
Given an integer n, return true if it is a power of three. Otherwise, return false.
An integer n is a power of three, if there exists an integer x such that n == 3x.
Example 1:
Input: n = 27
Output: true
Explanation: 27 = 33
Example 2:
Input: n = 0
Output: false
Explanation: There is no x where 3x = 0.
Example 3:
Input: n = -1
Output: false
Explanation: There is no x where 3x = (-1).
Constraints:
-231 <= n <= 231 - 1
Follow up: Could you solve it without loops/recursion?
*/
