Java program to calculate subset in o(n) time complexity using ArratList

1. Brutforce:

1. for(int i = 0; i < len; i++) {  
2.             //This loop adds the next character every iteration for the subset to form and add it to the array  
3.             for(int j = i; j < len; j++) {  
4.                 arr[temp] = str.substring(i, j+1);  
5.                 temp++;  
6.             }  
7.         }  

Subset can be implemented with the concept of decision tree:

How we can implement decision tree in code is:

CODE in JAVA: