检查数字是否只设置了第一位和最后一位|设置2-yiteyi-C++库

给定一个正整数n，检查在n的二进制表示中是否只设置了第一位和最后一位。打印“是”或“否”。 例如：

null

输入：9 输出：是的（9） 10=（1001）2，仅第一个和第二个最后一位已设置。输入：15 输出：否（15） 10=（1111）2，第一个和最后一个除外还设置了其他位。

我们已经讨论了一个解决方案在这里本文讨论了一个更简单的解决方案。

C++

                         // C++ to check whether the number has only                       
                         // first and last bits set                       
                         #include <bits/stdc++.h>                       
                         using                                     namespace                                     std;                       
           
                         // function to check whether the number has only                       
                         // first and last bits set                       
                         bool                                     onlyFirstAndLastAreSet(unsigned                                     int                                     n)                       
                         {                       
                                                 if                                     (n == 1)                       
                                                 return                                     true                                     ;                       
                                                 if                                     (n == 2)                       
                                                 return                                     false                                     ;                       
                                                 return                                     (((n - 1) & (n - 2)) == 0);                       
                         }                       
           
                         // Driver program to test above                       
                         int                                     main()                       
                         {                       
                                                 unsigned                                     int                                     n = 9;                       
                                                 if                                     (onlyFirstAndLastAreSet(n))                       
                                                 cout <<                                     "Yes"                                     ;                       
                                                 else                       
                                                 cout <<                                     "No"                                     ;                       
           
                                                 return                                     0;                       
                         }                       

JAVA

                         // Java to check whether                       
                         // the number has only                       
                         // first and last bits set                       
           
                         class                                     GFG                       
                         {                       
                         // function to check whether                       
                         // the number has only                       
                         // first and last bits set                       
                         static                                     boolean                                     onlyFirstAndLastAreSet(                                     int                                     n)                       
                         {                       
                                                 if                                     (n ==                                     1                                     )                       
                                                 return                                     true                                     ;                       
                                                 if                                     (n ==                                     2                                     )                       
                                                 return                                     false                                     ;                       
                                                 return                                     (((n -                                     1                                     ) &                       
                                                 (n -                                     2                                     )) ==                                     0                                     );                       
                         }                       
           
                         // Driver Code                       
                         public                                     static                                     void                                     main(String[] args)                       
                         {                       
                                                 int                                     n =                                     9                                     ;                       
                                                 if                                     (onlyFirstAndLastAreSet(n))                       
                                                 System.out.println(                                     "Yes"                                     );                       
                                                 else                       
                                                 System.out.println(                                     "No"                                     );                       
                         }                       
                         }                       
           
                         // This code is contributed                       
                         // by Smitha                       

Python3

                         # Python 3 to check whether                       
                         # the number has only                       
                         # first and last bits set                       
           
                         # function to check whether                       
                         # the number has only                       
                         # first and last bits set                       
                         def                                     onlyFirstAndLastAreSet(n):                       
           
                                                 if                                     (n                                     =                                     =                                     1                                     ):                       
                                                 return                                     True                       
                                                 if                                     (n                                     =                                     =                                     2                                     ):                       
                                                 return                                     False                       
           
                                                 return                                     (((n                                     -                                     1                                     ) &                       
                                                 (n                                     -                                     2                                     ))                                     =                                     =                                     0                                     )                       
           
                         # Driver Code                       
                         n                                     =                                     9                       
                         if                                     (onlyFirstAndLastAreSet(n)):                       
                                                 print                                     (                                     "Yes"                                     )                       
                         else                                     :                       
                                                 print                                     (                                     "No"                                     )                       
                                   
                         # This code is contributed                       
                         # by Smitha                       

C#

                         // C# to check whether                       
                         // the number has only                       
                         // first and last bits set                       
                         using                                     System;                       
           
                         class                                     GFG                       
                         {                       
                         // function to check whether                       
                         // the number has only                       
                         // first and last bits set                       
                         static                                     bool                                     onlyFirstAndLastAreSet(                                     int                                     n)                       
                         {                       
                                                 if                                     (n == 1)                       
                                                 return                                     true                                     ;                       
                                                 if                                     (n == 2)                       
                                                 return                                     false                                     ;                       
                                                 return                                     (((n - 1) &                       
                                                 (n - 2)) == 0);                       
                         }                       
           
                         // Driver Code                       
                         public                                     static                                     void                                     Main()                       
                         {                       
                                                 int                                     n = 9;                       
                                                 if                                     (onlyFirstAndLastAreSet(n))                       
                                                 Console.Write(                                     "Yes"                                     );                       
                                                 else                       
                                                 Console.Write(                                     "No"                                     );                       
                         }                       
                         }                       
           
                         // This code is contributed                       
                         // by Smitha                       

PHP

                         <?php                       
                         // PHP to check whether the                       
                         // number has only first and                       
                         // last bits set                       
           
                         // function to check whether                       
                         // the number has only first                       
                         // and last bits set                       
                         function                                     onlyFirstAndLastAreSet(                                     $n                                     )                       
                         {                       
                                                 if                                     (                                     $n                                     == 1)                       
                                                 return                                     true;                       
                                                 if                                     (                                     $n                                     == 2)                       
                                                 return                                     false;                       
                                                 return                                     (((                                     $n                                     - 1) &                       
                                                 (                                     $n                                     - 2)) == 0);                       
                         }                       
           
                         // Driver Code                       
                         $n                                     = 9;                       
                         if                                     (onlyFirstAndLastAreSet(                                     $n                                     ))                       
                                                 echo                                     "Yes"                                     ;                       
                         else                       
                                                 echo                                     "No"                                     ;                       
                                   
                         // This code is contributed                       
                         // by Smitha                       
                         ?>                       

Javascript

                         <script>                       
           
                         // javascript to check whether                       
                         // the number has only                       
                         // first and last bits set                       
           
                         // function to check whether                       
                         // the number has only                       
                         // first and last bits set                       
                         function                                     onlyFirstAndLastAreSet(n)                       
                         {                       
                                                 if                                     (n == 1)                       
                                                 return                                     true                                     ;                       
                                                 if                                     (n == 2)                       
                                                 return                                     false                                     ;                       
                                                 return                                     (((n - 1) &                       
                                                 (n - 2)) == 0);                       
                         }                       
           
                         // Driver Code                       
           
                         var                                     n = 9;                       
                         if                                     (onlyFirstAndLastAreSet(n))                       
                                                 document.write(                                     "Yes"                                     );                       
                         else                       
                                                 document.write(                                     "No"                                     );                       
           
                         // This code contributed by shikhasingrajput                       
           
                         </script>                       

输出：

Yes

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