import numpy as np
def checkDifferent(iniString):
    # write code here
    a = np.unique(iniString)
    if (a == iniString):
        return True
    else:
        return False
    
    
    
    
checkDifferent("fbcdbea")

class Different:
    def checkDifferent(self, iniString):
        # write code here
        for item in iniString:
            
            index = iniString.index(item)
            
            for s in iniString[index+1:]:
                if (s == item):
                    return False
        return True
 

java：

import java.util.*;

public class Different {
    public boolean checkDifferent(String iniString) {
        // write code here
        char[] a = iniString.toCharArray(); // cannot directly iterrate string
        for (char item:a)
        {
           
            int index = iniString.indexOf(item);
            
            for (char s :Arrays.copyOfRange(a, index+1, a.length))
            {
                if (s == item)
                {return false;}
            }
        }
        return true;
    }
}