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package com.hmkcode;
public class Combination {
public static void main(String[] args){
Object[] elements = new Object[] {'A','B','C','D','E'};
combination(elements,3);
}
public static void combination(Object[] elements, int K){
// get the length of the array
// e.g. for {'A','B','C','D'} => N = 4
int N = elements.length;
if(K > N){
System.out.println("Invalid input, K > N");
return;
}
// calculate the possible combinations
c(N,K);
// init combination index array
int combination[] = new int[K];
int r = 0; // index for combination array
int i = 0; // index for elements array
while(r >= 0){
// forward step if i < (N + (r-K))
if(i = 0)
i = combination[r]+1;
}
}
}
private static int c(int n, int r){
int nf=fact(n);
int rf=fact(r);
int nrf=fact(n-r);
int npr=nf/nrf;
int ncr=npr/rf;
System.out.println("C("+n+","+r+") = "+ ncr);
return ncr;
}
private static int fact(int n)
{
if(n == 0)
return 1;
else
return n * fact(n-1);
}
private static void print(int[] combination, Object[] elements){
String output = "";
for(int z = 0 ; z < combination.length;z++){
output += elements[combination[z]];
}
System.out.println(output);
}
}