0693. Binary Number with Alternating Bits

https://leetcode.com/problems/binary-number-with-alternating-bits

Description

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.

Example 4:

**Input:** n = 10
**Output:** true
**Explanation:** The binary representation of 10 is: 1010.

Example 5:

**Input:** n = 3
**Output:** false

Constraints:

• 1 <= n <= 231 - 1

ac

class Solution {
    public boolean hasAlternatingBits(int n) {
        int val = n ^ (n >> 1); // should be all 1s, if n is valid
        return ((val + 1) & val) == 0; // all 1s plus 1 should be: 1000...., so the & should give us all 0s
    }
}

/*
1) int val = n ^ (n >> 1); // should be all 1s, if n is valid; 2) return ((val + 1) & val) == 0; // all 1s plus 1 should be: 1000...., so the & should give us all 0s
*/