Find whether a given number is a power of 4 or not
Given an integer n, find whether it is a power of 4 or not.
Example :
Input : 16 Output : 16 is a power of 4 Input : 20 Output : 20 is not a power of 4
We strongly recommend that you click here and practice it, before moving on to the solution.
1. A simple method is to take log of the given number on base 4, and if we get an integer then number is power of 4.
2. Another solution is to keep dividing the number by 4, i.e, do n = n/4 iteratively. In any iteration, if n%4 becomes non-zero and n is not 1 then n is not a power of 4, otherwise n is a power of 4.
C++
// C++ program to find whether a given // number is a power of 4 or not #include<iostream> using namespace std; #define bool int class GFG { /* Function to check if x is power of 4*/public : bool isPowerOfFour(int n) { if(n == 0) return 0; while(n != 1) { if(n % 4 != 0) return 0; n = n / 4; } return 1; } }; /*Driver code*/int main() { GFG g; int test_no = 64; if(g.isPowerOfFour(test_no)) cout << test_no << " is a power of 4"; else cout << test_no << "is not a power of 4"; getchar(); } // This code is contributed by SoM15242 |
chevron_right
filter_none
C
#include<stdio.h> #define bool int /* Function to check if x is power of 4*/bool isPowerOfFour(int n) { if(n == 0) return 0; while(n != 1) { if(n % 4 != 0) return 0; n = n / 4; } return 1; } /*Driver program to test above function*/int main() { int test_no = 64; if(isPowerOfFour(test_no)) printf("%d is a power of 4", test_no); else printf("%d is not a power of 4", test_no); getchar(); } |
chevron_right
filter_none
Java
// Java code to check if given // number is power of 4 or not class GFG { // Function to check if // x is power of 4 static int isPowerOfFour(int n) { if(n == 0) return 0; while(n != 1) { if(n % 4 != 0) return 0; n = n / 4; } return 1; } // Driver program public static void main(String[] args) { int test_no = 64; if(isPowerOfFour(test_no) == 1) System.out.println(test_no + " is a power of 4"); else System.out.println(test_no + "is not a power of 4"); } } // This code is contributed // by prerna saini |
chevron_right
filter_none
Python3
# Python3 program to check if given # number is power of 4 or not # Function to check if x is power of 4 def isPowerOfFour(n): if (n == 0): return False while (n != 1): if (n % 4 != 0): return False n = n // 4 return True # Driver code test_no = 64if(isPowerOfFour(64)): print(test_no, 'is a power of 4') else: print(test_no, 'is not a power of 4') # This code is contributed by Danish Raza |
chevron_right
filter_none
C#
// C# code to check if given // number is power of 4 or not using System; class GFG { // Function to check if // x is power of 4 static int isPowerOfFour(int n) { if (n == 0) return 0; while (n != 1) { if (n % 4 != 0) return 0; n = n / 4; } return 1; } // Driver code public static void Main() { int test_no = 64; if (isPowerOfFour(test_no) == 1) Console.Write(test_no + " is a power of 4"); else Console.Write(test_no + " is not a power of 4"); } } // This code is contributed by Sam007 |
chevron_right
filter_none
PHP
<?php // PHP code to check if given // number is power of 4 or not // Function to check if // x is power of 4 function isPowerOfFour($n) { if($n == 0) return 0; while($n != 1) { if($n % 4 != 0) return 0; $n = $n / 4; } return 1; } // Driver Code $test_no = 64; if(isPowerOfFour($test_no)) echo $test_no," is a power of 4"; else echo $test_no," is not a power of 4"; // This code is contributed by Rajesh ?> |
chevron_right
filter_none
Output :
64 is a power of 4
3. A number n is a power of 4 if following conditions are met.
a) There is only one bit set in the binary representation of n (or n is a power of 2)
b) The count of zero bits before the (only) set bit is even.
For example: 16 (10000) is power of 4 because there is only one bit set and count of 0s before the set bit is 4 which is even.
Thanks to Geek4u for suggesting the approach and providing the code.
C++
// C++ program to check // if given number is // power of 4 or not #include<bits/stdc++.h> using namespace std; bool isPowerOfFour(unsigned int n) { int count = 0; /*Check if there is only one bit set in n*/ if ( n && !(n&(n-1)) ) { /* count 0 bits before set bit */ while(n > 1) { n >>= 1; count += 1; } /*If count is even then return true else false*/ return (count%2 == 0)? 1 :0; } /* If there are more than 1 bit set then n is not a power of 4*/ return 0; } /*Driver code*/int main() { int test_no = 64; if(isPowerOfFour(test_no)) cout << test_no << " is a power of 4" ; else cout << test_no << " is not a power of 4"; } // This code is contributed by Shivi_Aggarwal |
chevron_right
filter_none
C
#include<stdio.h> #define bool int bool isPowerOfFour(unsigned int n) { int count = 0; /*Check if there is only one bit set in n*/ if ( n && !(n&(n-1)) ) { /* count 0 bits before set bit */ while(n > 1) { n >>= 1; count += 1; } /*If count is even then return true else false*/ return (count%2 == 0)? 1 :0; } /* If there are more than 1 bit set then n is not a power of 4*/ return 0; } /*Driver program to test above function*/int main() { int test_no = 64; if(isPowerOfFour(test_no)) printf("%d is a power of 4", test_no); else printf("%d is not a power of 4", test_no); getchar(); } |
chevron_right
filter_none
Java
// Java program to check // if given number is // power of 4 or not import java.io.*; class GFG { static int isPowerOfFour(int n) { int count = 0; /*Check if there is only one bit set in n*/ int x = n & (n - 1); if ( n > 0 && x == 0) { /* count 0 bits before set bit */ while(n > 1) { n >>= 1; count += 1; } /*If count is even then return true else false*/ return (count % 2 == 0) ? 1 : 0; } /* If there are more than 1 bit set then n is not a power of 4*/ return 0; } // Driver Code public static void main(String[] args) { int test_no = 64; if(isPowerOfFour(test_no)>0) System.out.println(test_no + " is a power of 4"); else System.out.println(test_no + " is not a power of 4"); } } // This code is contributed by mits |
chevron_right
filter_none
Python3
# Python3 program to check if given # number is power of 4 or not # Function to check if x is power of 4 def isPowerOfFour(n): count = 0 # Check if there is only one # bit set in n if (n and (not(n & (n - 1)))): # count 0 bits before set bit while(n > 1): n >>= 1 count += 1 # If count is even then return # true else false if(count % 2 == 0): return True else: return False # Driver code test_no = 64if(isPowerOfFour(64)): print(test_no, 'is a power of 4') else: print(test_no, 'is not a power of 4') # This code is contribued by Danish Raza |
chevron_right
filter_none
C#
// C# program to check if given // number is power of 4 or not using System; class GFG { static int isPowerOfFour(int n) { int count = 0; /*Check if there is only one bit set in n*/ int x = n & (n-1); if ( n > 0 && x == 0) { /* count 0 bits before set bit */ while(n > 1) { n >>= 1; count += 1; } /*If count is even then return true else false*/ return (count % 2 == 0) ? 1 : 0; } /* If there are more than 1 bit set then n is not a power of 4*/ return 0; } /*Driver program to test above function*/ static void Main() { int test_no = 64; if(isPowerOfFour(test_no)>0) Console.WriteLine("{0} is a power of 4", test_no); else Console.WriteLine("{0} is not a power of 4", test_no); } } // This Code is Contributed by mits |
chevron_right
filter_none
PHP
<?php function isPowerOfFour($n) { $count = 0; /*Check if there is only one bit set in n*/if ( $n && !($n&($n-1)) ) { /* count 0 bits before set bit */ while($n > 1) { $n >>= 1; $count += 1; } /*If count is even then return true else false*/ return ($count%2 == 0)? 1 :0; } /* If there are more than 1 bit set then n is not a power of 4*/return 0; } /*Driver program to test above function*/ $test_no = 64; if(isPowerOfFour($test_no)) echo $test_no, " is a power of 4"; else echo $test_no, " not is a power of 4"; #This Code is Contributed by Ajit ?> |
chevron_right
filter_none
Output:
64 is a power of 4
4. A number n is a power of 4 if following conditions are met.
a) There is only one bit set in the binary representation of n (or n is a power of 2)
b) The bits don’t AND(&) any part of the pattern 0xAAAAAAAA
For example: 16 (10000) is power of 4 because there is only one bit set and 0x10 & 0xAAAAAAAA is zero.
Thanks to Sarthak Sahu for suggesting the approach.
C++
// C++ program to check // if given number is // power of 4 or not #include<bits/stdc++.h> using namespace std; bool isPowerOfFour(unsigned int n) { return n !=0 && ((n&(n-1)) == 0) && !(n & 0xAAAAAAAA); } /*Driver code*/int main() { int test_no = 64; if(isPowerOfFour(test_no)) cout << test_no << " is a power of 4" ; else cout << test_no << " is not a power of 4"; } |
chevron_right
filter_none
C
// C program to check // if given number is // power of 4 or not #include<stdio.h> #define bool int bool isPowerOfFour(unsigned int n) { return n != 0 && ((n&(n-1)) == 0) && !(n & 0xAAAAAAAA); } /*Driver program to test above function*/int main() { int test_no = 64; if(isPowerOfFour(test_no)) printf("%d is a power of 4", test_no); else printf("%d is not a power of 4", test_no); getchar(); } |
chevron_right
filter_none
Java
// Java program to check // if given number is // power of 4 or not import java.io.*; class GFG { static boolean isPowerOfFour(int n) { return n != 0 && ((n&(n-1)) == 0) && (n & 0xAAAAAAAA) == 0; } // Driver Code public static void main(String[] args) { int test_no = 64; if(isPowerOfFour(test_no)) System.out.println(test_no + " is a power of 4"); else System.out.println(test_no + " is not a power of 4"); } } |
chevron_right
filter_none
Python3
# Python3 program to check
# if given number is
# power of 4 or not
def isPowerOfFour(n):
return (n != 0 and
((n & (n – 1)) == 0) and
not(n & 0xAAAAAAAA));
# Driver code
test_no = 64;
if(isPowerOfFour(test_no)):
print(test_no ,”is a power of 4″);
else:
print(test_no , “is not a power of 4”);
# This code contributed by Rajput-Ji
C#
// C# program to check // if given number is // power of 4 or not using System; class GFG { static bool isPowerOfFour(int n) { return n != 0 && ((n&(n-1)) == 0) && (n & 0xAAAAAAAA) == 0; } // Driver Code static void Main() { int test_no = 64; if(isPowerOfFour(test_no)) Console.WriteLine("{0} is a power of 4", test_no); else Console.WriteLine("{0} is not a power of 4", test_no); } } // This code is contributed by mohit kumar 29 |
chevron_right
filter_none
Output:
64 is a power of 4
Why 0xAAAAAAAA ? This is because the bit representation is of powers of 2 that are not of 4. Like 2, 8, 32 so on..
Please write comments if you find any of the above codes/algorithms incorrect, or find other ways to solve the same problem.
Recommended Posts:
- Find the super power of a given Number
- Find last five digits of a given five digit number raised to power five
- Find maximum power of a number that divides a factorial
- Find power of power under mod of a prime
- Check if given number is a power of d where d is a power of 2
- Find value of y mod (2 raised to power x)
- Find whether a given integer is a power of 3 or not
- Program to find whether a no is power of two
- Highest power of a number that divides other number
- Given two numbers as strings, find if one is a power of other
- Find multiple of x closest to or a ^ b (a raised to power b)
- Find unit digit of x raised to power y
- Number of pairs whose sum is a power of 2
- Check if a number is power of 8 or not
- Power of a prime number ‘r’ in n!
