Algorithm
Problem Name: 693. Binary Number with Alternating Bits
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 <= 231 - 1
Code Examples
#1 Code Example with C Programming
Code -
C Programming
unsigned int first_bit_on(unsigned int k, unsigned int sz) {
unsigned int m = sz / 2;
if (k == 1) return 1;
if ((k >> m) == 0) {
return first_bit_on(k, m);
}
return m + first_bit_on(k >> m, m);
}
bool hasAlternatingBits(int n){
unsigned int k = n;
unsigned int b = first_bit_on(n, 32);
//printf("%d\n", b);
return (k ^ (k >> 1)) == ((unsigned int)1 << b) - 1 ? true : false;
}
Input
Output
#2 Code Example with C++ Programming
Code -
C++ Programming
class Solution {
public:
bool hasAlternatingBits(int n) {
while(n)
if(!((n & 1) ^ ((n >> 1) & 1))) return false;
else n >>= 1;
return true;
}
};
Input
Output
#3 Code Example with Java Programming
Code -
Java Programming
class Solution {
public boolean hasAlternatingBits(int n) {
Integer prev = null;
while (n > 0) {
int rem = n % 2;
n /= 2;
if (prev == null || prev != rem) {
prev = rem;
} else {
return false;
}
}
return true;
}
}
Input
Output
#4 Code Example with Javascript Programming
Code -
Javascript Programming
const hasAlternatingBits = function(n) {
const str = bin(n);
for (let i = 1, prev = str.charAt(0); i < str.length; i++) {
if (str.charAt(i) === prev) {
return false;
}
prev = str.charAt(i);
}
return true;
};
function bin(num) {
return (num >>> 0).toString(2);
}
Input
Output
#5 Code Example with Python Programming
Code -
Python Programming
class Solution:
def hasAlternatingBits(self, n: int) -> bool:
return all(a != b for a, b in zip(bin(n)[2:], bin(n)[3:]))
Input
Output
#6 Code Example with C# Programming
Code -
C# Programming
namespace LeetCode
{
public class _0693_BinaryNumberWithAlternatingBits
{
public bool HasAlternatingBits(int n)
{
var prev = n & 1;
n >>= 1;
while (n > 0)
{
var current = n & 1;
if (current == prev) return false;
prev = current;
n >>= 1;
}
return true;
}
}
}
Input
Output