is String having Unique Character Using Array, Time: O(n), Space: O(1) - Java Algorithm

Java examples for Algorithm:String

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Description

is String having Unique Character Using Array, Time: O(n), Space: O(1)

Demo Code

public class Main {
  public static boolean isUnique(String str){
    // Time: O(n), Space: O(1)
    if(str.length()<=1) return true;
    else if(str.length()>256) return false;
    Character[] characters=new Character[256];
    int val;
    for(int i=0; i<str.length(); i++){
      val=str.charAt(i);
      if(characters[val]==null) characters[val]=str.charAt(i);
      else return false;
    }/*ww  w.ja  v a2 s . c  om*/
    return true;
  }
  // Test
  public static void main(String[] args){
    String str="Hello";
    System.out.print(isUnique(str)+" ");
    String str_2="";
    System.out.print(isUnique(str_2)+" ");
    String str_3="He";
    System.out.print(isUnique(str_3)+" ");
    String str_4="  ";
    System.out.print(isUnique(str_4)+" ");
  }
}

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