leetcode-693-easy

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

思路一：遍历每位 bit，检测是否符合条件

public boolean hasAlternatingBits(int n) {
    int bit = (n & 1) == 1 ? 1 : 0;
    n >>= 1;
    while (n > 0) {
        if ((n & 1) == 1) {
            if (bit == 1) {
                return false;
            }

            bit = 1;
        } else {
            if (bit == 0) {
                return false;
            }

            bit = 0;
        }

        n >>= 1;
    }

    return true;
}