Question
Formatted question description: https://leetcode.ca/all/231.html
231 Power of Two
Given an integer, write a function to determine if it is a power of two.
Example 1:
Input: 1
Output: true
Explanation: 2^0 = 1
Example 2:
Input: 16
Output: true
Explanation: 2^4 = 16
Example 3:
Input: 218
Output: false
Algorithm
Observe the characteristics of the binary notation of the power of 2:
1 2 4 8 16 ....
1 10 100 1000 10000 ...
The power of 2 has only one 1, and the rest is 0s, so our problem-solving idea is to determine whether the lowest bit is 1 each time, then shift to the right, and finally count the number of 1s to determine whether it is Power of 2
Code
Java
public class Power_of_Two {
class Solution {
public boolean isPowerOfTwo(int n) {
int cnt = 0;
while (n > 0) {
cnt += (n & 1);
n >>= 1;
}
return cnt == 1;
}
}
}