CC--Q1.1

1.1 Is Unique: Implement an algorithm to determine if a string has all unique characters.What if you cannot use additional data structures?

Assuming all characters are ASCII.

public static boolean isUniqueChars(String str) {
    if (str.length() > 256) { 
        return false;
    }
    int checker = 0;
    for (int i = 0; i < str.length(); i++) {
        int val = str.charAt(i) - 'a';
        if ((checker & (1 << val)) > 0) return false;
        checker |= (1 << val);
    }
    return true;
}

Or just use a boolean array of size 256 to check duplicate.