isunique.md

Is Unique

Implement an algorithm to determine if a string has all unique characters.

boolean isUniqueChars(String str) {
    if (str.length() > 128) return false;
    boolean[] char_set = new boolean[128];
    for (int i = 0; i < str.length(); i++) {
        int val = str.charAt(i);
        if (char_set[i]) {
            return false;
        }
        char_set[val] = true;
    }
    return true;
}