Q1_1.java

public class Q1_1{
  public static void main(String args[]){
    String test = "";
    System.out.println(checkUnique(test));
  }
  public static boolean checkUnique(String s){
    boolean[] signs = new boolean[256];
    
    for(int i =0; i<s.length();i++){
      if(signs[s.charAt(i)])
        return false;
      else 
        signs[s.charAt(i)]=true;
    }
    return true;
  }
  

}