private int formNumber(int input[], int start, int end){
        int num = 0;
        for(int i=start; i <=end; i++){
            num = num*10 + input[i];
        }
        return num;
    }
Generate all combination of size k and less of adjacent numbers
e.g 1,2,3,4 k = 2
1 2 3 4
12 3 4
1 23 4
1 2 3 34
12 34
@author tusroy
src/com/interview/recursion/AllAdjacentCombination.java