How to find smallest substring which contains all characters from a given string?

Question

I have recently come across an interesting question on strings. Suppose you are given following:

Input string1: \"this is a test string\"
Input strin         


        

Answer 1

    String s = "xyyzyzyx";
    String s1 = "xyz";
    String finalString ="";
    Map hm = new HashMap<>();
    if(s1!=null && s!=null && s.length()>s1.length()){
        for(int i =0;i t = new HashMap<>();
        int start =-1;
         for(int j=0;js.length()){
                             break;
                         }
                         start = j;
                     }
                 }
                 if(hm.equals(t)){
                    t = new HashMap<>();
                    if(finalString.length()