Check if a number is divisible by all prime divisors of another number
Given two integers. We need to find if the first number x is divisible by all prime divisors of y.
Examples :
Input : x = 120, y = 75 Output : Yes Explanation : 120 = (2^3)*3*5 75 = 3*(5^2) 120 is divisible by both 3 and 5 which are the prime divisors of 75. Hence, answer is "Yes". Input : x = 15, y = 6 Output : No Explanation : 15 = 3*5. 6 = 2*3, 15 is not divisible by 2 which is a prime divisor of 6. Hence, answer is "No".
A simple solution is to find all prime factors of y. For every prime factor, check if it divides x or not.
An efficient solution is based on the below facts.
1) if y == 1, then it no prime divisors. Hence answer is “Yes”
2) We find GCD of x and y.
a) If GCD == 1, then clearly there are no common divisors of x and y, hence answer is “No”.
b) If GCD > 1, the GCD contains prime divisors which divide x also. Now, we have all unique prime divisors if and only if y/GCD has such unique prime divisor. So we have to find uniqueness for pair (x, y/GCD) using recursion.
Below is the implementation of the above approach:
C++
// CPP program to find if all prime factors // of y divide x. #include <bits/stdc++.h> using namespace std; // Returns true if all prime factors of y // divide x. bool isDivisible( int x, int y) { if (y == 1) return true ; int z = __gcd(x, y); if (z == 1) return false ; return isDivisible(x, y / z); } // Driver Code int main() { int x = 18, y = 12; if (isDivisible(x, y)) cout << "Yes" << endl; else cout << "No" << endl; return 0; } |
Java
// Java program to find if all // prime factors of y divide x. public class Divisible { public static int gcd( int a, int b) { return b == 0 ? a : gcd(b, a % b); } // Returns true if all prime factors // of y divide x. static boolean isDivisible( int x, int y) { if (y == 1 ) return true ; int z = gcd(x, y); if (z == 1 ) return false ; return isDivisible(x, y / z); } // Driver program to test above functions public static void main(String[] args) { int x = 18 , y = 12 ; if (isDivisible(x, y)) System.out.println( "Yes" ); else System.out.println( "No" ); } }; // This code is contributed by Prerna Saini |
Python3
# python program to find if all # prime factors of y divide x. def gcd(a, b): if (b = = 0 ): return a else : return gcd(b, a % b) # Returns true if all prime # factors of y divide x. def isDivisible(x,y): if (y = = 1 ): return 1 z = gcd(x, y); if (z = = 1 ): return false; return isDivisible(x, y / z); # Driver Code x = 18 y = 12 if (isDivisible(x, y)): print ( "Yes" ) else : print ( "No" ) # This code is contributed by Sam007 |
C#
// C# program to find if all // prime factors of y divide x. using System; class GFG { public static int gcd( int a, int b) { return b == 0 ? a : gcd(b, a % b); } // Returns true if all prime factors // of y divide x. static bool isDivisible( int x, int y) { if (y == 1) return true ; int z = gcd(x, y); if (z == 1) return false ; return isDivisible(x, y / z); } // Driver program to test above functions public static void Main() { int x = 18, y = 12; if (isDivisible(x, y)) Console.WriteLine( "Yes" ); else Console.WriteLine( "No" ); } } // This code is contributed by vt_m. |
PHP
<?php // PHP program to find if all // prime factors of y divide x. function gcd ( $a , $b ) { return $b == 0 ? $a : gcd( $b , $a % $b ); } // Returns true if all prime // factors of y divide x. function isDivisible( $x , $y ) { if ( $y == 1) return true; $z = gcd( $x , $y ); if ( $z == 1) return false; return isDivisible( $x , $y / $z ); } // Driver Code $x = 18; $y = 12; if (isDivisible( $x , $y )) echo "Yes" ; else echo "No" ; // This code is contributed by Sam007 ?> |
Javascript
<script> // Javascript program to find if all // prime factors of y divide x. function gcd(a , b) { return b == 0 ? a : gcd(b, a % b); } // Returns true if all prime factors // of y divide x. function isDivisible(x , y) { if (y == 1) return true ; var z = gcd(x, y); if (z == 1) return false ; return isDivisible(x, y / z); } // Driver program to test above functions var x = 18, y = 12; if (isDivisible(x, y)) document.write( "Yes" ); else document.write( "No" ); // This code is contributed by Amit Katiyar </script> |
Yes
Time Complexity: The time complexity for calculating GCD is O(log min(x, y)), and recursion will terminate after log y steps because we are reducing it by a factor greater than one. Overall Time complexity: O(log2y)
Auxiliary Space: O(log min(x, y))
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