1.1.cc

// Time: n Space: n
bool HasUniqueChars(char* str, int n) {
  bitset<256> s;
  for (size_t i = 0; i < n; ++i) {
    int val = str[i];
    if (s[val]) return false;
    else s[val] = true;
  }
  return true;
} 

// assume class string to use STL sort()
// Time: n * log (n) Space: 0
bool HasUniqueChars1(string s) {
  sort(s.begin(), s.end());
  for (size_t i = 1; i < s.size(); ++i) {
    if (s[i] == s[i - 1]) return false;
  }
  return true;
}