Given an integer n, return true if it is a power of four. Otherwise, return false.
An integer n is a power of four, if there exists an integer x such that n == 4x.
Example 1:
Input: n = 16 Output: true
Example 2:
Input: n = 5 Output: false
Example 3:
Input: n = 1 Output: true
Constraints:
-231 <= n <= 231 - 1Follow up: Could you solve it without loops/recursion?
class Solution {
public:
bool isPowerOfFour(int n) {
if(n<=0) return false;
float a = log10(n)/log10(4);
return floor(a)==a;
}
};class Solution {
public boolean isPowerOfFour(int n) {
if (n <= 0)
return false;
double expr = Math.log10(n) / Math.log10(4);
return expr == Math.floor(expr);
}
}class Solution {
public boolean isPowerOfFour(int n) {
if (n <= 0)
return false;
double expr = Math.log10(n) / Math.log10(4);
return expr == Math.floor(expr);
}
}