I have seen that such a function exists for BigInteger, i.e. BigInteger#gcd. Are there other functions in Java which also work for other types (int, long or Integer)? It seems this would make sense as java.lang.Math.gcd (with all kinds of overloads) but it is not there. Is it somewhere else?
(Don't confuse this question with "how do I implement this myself", please!)
public int gcd(int num1, int num2) {
int max = Math.abs(num1);
int min = Math.abs(num2);
while (max > 0) {
if (max < min) {
int x = max;
max = min;
min = x;
}
max %= min;
}
return min;
}
This method uses the Euclid’s algorithm to get the "Greatest Common Divisor" of two integers. It receives two integers and returns the gcd of them. just that easy!
Is it somewhere else?
Apache! - it has both gcd and lcm, so cool!
However, due to profoundness of their implementation, it's slower compared to simple hand-written version (if it matters).
Those GCD functions provided by Commons-Math and Guava have some differences.
ArithematicException.class only for Integer.MIN_VALUE or Long.MIN_VALUE.
IllegalArgumentException.class for any negative values.The % going to give us the gcd Between two numbers, it means:-
% or mod of big_number/small_number are =gcd,
and we write it on java like this big_number % small_number.
EX1: for two integers
public static int gcd(int x1,int x2)
{
if(x1>x2)
{
if(x2!=0)
{
if(x1%x2==0)
return x2;
return x1%x2;
}
return x1;
}
else if(x1!=0)
{
if(x2%x1==0)
return x1;
return x2%x1;
}
return x2;
}
EX2: for three integers
public static int gcd(int x1,int x2,int x3)
{
int m,t;
if(x1>x2)
t=x1;
t=x2;
if(t>x3)
m=t;
m=x3;
for(int i=m;i>=1;i--)
{
if(x1%i==0 && x2%i==0 && x3%i==0)
{
return i;
}
}
return 1;
}