leetcode 693. Binary Number with Alternating Bits 二进制的数据是否交替出现+暴力判断

向右看齐 2022-06-03 08:39 106阅读 0赞

Given a positive integer, check whether it has alternating bits: namely, if two adjacent bits will always have different values.

Example 1:  
Input: 5  
Output: True  
Explanation:  
The binary representation of 5 is: 101  
Example 2:  
Input: 7  
Output: False  
Explanation:  
The binary representation of 7 is: 111.  
Example 3:  
Input: 11  
Output: False  
Explanation:  
The binary representation of 11 is: 1011.  
Example 4:  
Input: 10  
Output: True  
Explanation:  
The binary representation of 10 is: 1010.

本题题意就是检查0和1是否是交替出现的，使用一个lastBit来表示上一位，然后逐位比较即可

代码如下：

#include <iostream>
    #include <vector>
    #include <map>
    #include <set>
    #include <queue>
    #include <stack>
    #include <string>
    #include <climits>
    #include <algorithm>
    #include <sstream>
    #include <functional>
    #include <bitset>
    #include <numeric>
    #include <cmath>
    #include <regex>
    
    using namespace std;
    
    
    
    class Solution 
    {
    public:
        bool hasAlternatingBits(int n) 
        {
            int lastBit = -1;
            while (n > 0)
            {
                int a = n & 1;
                if (a == 1)
                {
                    if (lastBit == 1)
                        return false;
                    else
                        lastBit = 1;
                }
                else
                {
                    if (lastBit == 0)
                        return false;
                    else
                        lastBit = 0;
                }
                n = n >> 1;;
            }
            return true;
        }
    };