检查一个数字是否可以表示为幂|集2（使用Log）-yiteyi-C++库

检查一个数字是否可以表示为x^y（x提升为y的幂）给定一个正整数n，找出它是否可以表示为x^y，其中y>1，x>0。x和y都是整数。 例如：

null

Input:  n = 8Output: true8 can be expressed as 2^3Input:  n = 49Output: true49 can be expressed as 7^2Input:  n = 48Output: false48 can't be expressed as x^y

推荐：请尝试你的方法 {IDE} 首先，在进入解决方案之前。

我们在下面的帖子中讨论了两种不同的方法。检查一个数字是否可以表示为x^y（x提升为y的幂） . 其思想是在从2到n的平方根的不同基数中找到logn。如果基数的logn变为整数，则结果为真，否则结果为假。

C++

                         // CPP program to find if a number                       
                         // can be expressed as x raised to                       
                         // power y.                       
                         #include <bits/stdc++.h>                       
                         using                                     namespace                                     std;                       
           
                         bool                                     isPower(unsigned                                     int                                     n)                       
                         {                       
                                                 // Find Log n in different bases                       
                                                 // and check if the value is an                       
                                                 // integer                       
                                                 for                                     (                                     int                                     x=2; x<=                                     sqrt                                     (n); x++) {                       
                                                 float                                     f =                                     log                                     (n) /                                     log                                     (x);                       
                                                 if                                     ((f - (                                     int                                     )f) == 0.0)                       
                                                 return                                     true                                     ;                       
                                                 }                       
                                                 return                                     false                                     ;                       
                         }                       
           
                         // Driver code                       
                         int                                     main()                       
                         {                       
                                                 for                                     (                                     int                                     i = 2; i < 100; i++)                       
                                                 if                                     (isPower(i))                       
                                                 cout << i <<                                     "  "                                     ;                       
                                                 return                                     0;                       
                         }                       

JAVA

                         // Java program to find if a number                       
                         // can be expressed as x raised to                       
                         // power y.                       
                         class                                     GFG {                       
                                   
                                                 static                                     boolean                                     isPower(                                     int                                     n)                       
                                                 {                       
                                                 // Find Log n in different                       
                                                 // bases and check if the                       
                                                 // value is an integer                       
                                                 for                                     (                                     int                                     x =                                     2                                     ; x <=                       
                                                 (                                     int                                     )Math.sqrt(n); x++)                       
                                                 {                       
                                                 float                                     f = (                                     float                                     )Math.log(n) /                       
                                                 (                                     float                                     ) Math.log(x);                       
                                   
                                                 if                                     ((f - (                                     int                                     )f) ==                                     0.0                                     )                       
                                                 return                                     true                                     ;                       
                                                 }                       
                                                 return                                     false                                     ;                       
                                                 }                       
                                   
                                                 // Driver code                       
                                                 public                                     static                                     void                                     main(String args[])                       
                                                 {                       
                                                 for                                     (                                     int                                     i =                                     2                                     ; i <                                     100                                     ; i++)                       
                                                 if                                     (isPower(i))                       
                                                 System.out.print( i +                                     " "                                     );                       
                                                 }                       
                         }                       
           
                         // This code is contributed by Sam007                       

Python3

                         # Python3 program to find if a number                       
                         # can be expressed as x raised to                       
                         # power y.                       
                         import                                     math                       
           
                         def                                     isPower(n):                       
           
                                                 # Find Log n in different                       
                                                 # bases and check if the                       
                                                 # value is an integer                       
                                                 for                                     x                                     in                                     range                                     (                                     2                                     ,                                     int                                     (math.sqrt(n))                                     +                                     1                                     ):                       
                                   
                                                 f                                     =                                     math.log(n)                                     /                                     math.log(x);                       
                                                 if                                     ((f                                     -                                     int                                     (f))                                     =                                     =                                     0.0                                     ):                       
                                                 return                                     True                                     ;                       
                                   
                                                 return                                     False                                     ;                       
           
                         # Driver code                       
                         for                                     i                                     in                                     range                                     (                                     2                                     ,                                     100                                     ):                       
                                                 if                                     (isPower(i)):                       
                                                 print                                     (i, end                                     =                                     " "                                     );                       
           
                         # This code is contributed by mits                       

C#

                         // C# program to find if a number                       
                         // can be expressed as x raised to                       
                         // power y.                       
                         using                                     System;                       
           
                         class                                     GFG                       
                         {                       
                                                 static                                     bool                                     isPower(                                     int                                     n)                       
                                                 {                       
                                                 // Find Log n in different                       
                                                 // bases and check if the                       
                                                 // value is an integer                       
                                                 for                                     (                                     int                                     x = 2;                       
                                                 x <= (                                     int                                     )Math.Sqrt(n); x++)                       
                                                 {                       
                                                 float                                     f = (                                     float                                     )Math.Log(n) /                       
                                                 (                                     float                                     ) Math.Log(x);                       
                                                 if                                     ((f - (                                     int                                     )f) == 0.0)                       
                                                 return                                     true                                     ;                       
                                                 }                       
                                                 return                                     false                                     ;                       
                                                 }                       
                                                 // Driver Code                       
                                                 public                                     static                                     void                                     Main()                       
                                                 {                       
                                                 for                                     (                                     int                                     i = 2; i < 100; i++)                       
                                                 if                                     (isPower(i))                       
                                                 Console.Write( i +                                     " "                                     );                       
                                                 }                       
                         }                       
           
                         // This code is contributed by Sam007                       

PHP

                         <?php                       
                         // PHP program to find if a number                       
                         // can be expressed as x raised to                       
                         // power y.                       
           
                         function                                     isPower(                                     $n                                     )                       
                         {                       
                                                 // Find Log n in different                       
                                                 // bases and check if the                       
                                                 // value is an integer                       
                                                 for                                     (                                     $x                                     = 2;                                     $x                                     <= sqrt(                                     $n                                     );                                     $x                                     ++)                       
                                                 {                       
                                                 $f                                     = log(                                     $n                                     ) / log(                                     $x                                     );                       
                                                 if                                     ((                                     $f                                     - (int)                                     $f                                     ) == 0.0)                       
                                                 return                                     true;                       
                                                 }                       
                                                 return                                     false;                       
                         }                       
           
                         // Driver code                       
                         for                                     (                                     $i                                     = 2;                                     $i                                     < 100;                                     $i                                     ++)                       
                                                 if                                     (isPower((int)                                     $i                                     ))                       
                                                 echo                                     $i                                     .                                     " "                                     ;                       
           
                         // This code is contributed by Sam007                       
                         ?>                       

Javascript

                         <script>                       
           
                         // javascript program to find if a number                       
                         // can be expressed as x raised to                       
                         // power y.                       
                         function                                     isPower(n) {                       
                                                 // Find Log n in different                       
                                                 // bases and check if the                       
                                                 // value is an integer                       
                                                 for                                     (x = 2; x <= parseInt( Math.sqrt(n)); x++)                       
                                                 {                       
                                                 var                                     f =  Math.log(n) /  Math.log(x);                       
           
                                                 if                                     ((f - parseInt( f)) == 0.0)                       
                                                 return                                     true                                     ;                       
                                                 }                       
                                                 return                                     false                                     ;                       
                                                 }                       
           
                                                 // Driver code                       
                                   
                                                 for                                     (i = 2; i < 100; i++)                       
                                                 if                                     (isPower(i))                       
                                                 document.write(i +                                     " "                                     );                       
           
                         // This code contributed by Rajput-Ji                       
           
                         </script>                       

输出：

4  8  9  16  25  27  32  36  49  64  81

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