import java.util.*;
import java.lang.*;
import java.io.*;
 
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		String s = "sabca";
		System.out.println(f(s.toCharArray()));
		System.out.println(g(new StringBuilder(s)));
	}
	public static String f(char[]s){String t="";for(char c:s)t+=t.contains(c+"")?"":c;return t;}
	public static String g(StringBuilder s){return new StringBuilder(s.reverse().toString().replaceAll("(?s)(.)(?=.*\\1)", "")).reverse().toString();}
}

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