Problem
Given a positive integer, check whether it has alternating bits: namely, if two adjacent bits will always have different values.
Example 1:
Input: n = 5
Output: true
Explanation: The binary representation of 5 is: 101
Example 2:
Input: n = 7
Output: false
Explanation: The binary representation of 7 is: 111.
Example 3:
Input: n = 11
Output: false
Explanation: The binary representation of 11 is: 1011.
Constraints:
1 <= n <= 2^31 - 1
Solution (Java)
class Solution {
public boolean hasAlternatingBits(int n) {
int prev = -1;
while (n != 0) {
int v = n & 1;
n = n >> 1;
if (prev == v) {
return false;
}
prev = v;
}
return true;
}
}
Explain:
nope.
Complexity:
- Time complexity : O(n).
- Space complexity : O(n).