CC1.1.java

/* 1.1 Implement an algorithm to determine if a string has all unique characters. Whatif you cannot use additional data structures? */
public class uniqueChar {
  public boolean allUnique(String s) {
    if(s==null || s.length()==0) return true;
    boolean[] appear = new boolean[256];
    for(int i=0; i<s.length(); i++) {
      if(appear[s.charAt(i)]) return false;
      appear[s.charAt(i)] = true;
    }
    return true;
  }
}