CC150 Practice

cc150-1.1

/*
1.1 Implement an algorithm to determine if a string has all unique characters. What if you can not use additional data structures?

 * 1.is it only  ascII charactors
 * 2.use an  char Array with total 256 readable  charactors 
 * check if  any of element in the array contains value
 * like boolean [] exsiting 
 * if(existing[char] == true)
 * return false;
 * else 
 * existing[char] == true;
 * 
 Time Complexity O(n) Space O(1)

*/
public class UniqueCharInString_1_1 {
  public static void main(String[] args){
				String testStr ="fdsfah";
		System.out.println(checkStringAllUniqu(testStr));
	}
	
 private static boolean checkStringAllUniqu(String str){
	 boolean[] allCharArray = new boolean[256];
	 if(str == null )
		 return true;
 	if(str.length()>256)
	  return false;
	 for(int i=0; i<str.length();i++){
		 int curchar = str.charAt(i);
		 if(allCharArray[curchar] )
			 return false;
		 allCharArray[curchar]=true;
		 
	 }
	 return true;
 }
}