After long search on net i found formula.
I have find formula Permutations with repetition on net
n^r Where n=length of string and r=combination choice
I want to make combination according to this formula n^r.
According to this formila n^r=9 combination possible here like this
Here i am trying but stuck in inner loop.
for( int k=0;k<nl;k++)
//Here i am stuck please help me