Determining if a string has all unique characters.

Problem

Implement an algorithm to determine if a string has all unique characters.
Example input: "abcdefg"
Example output: True
Example input: "aabbcc"
Example output: False

Solution

This solution is in JavaScript. Our A.I. can create solutions in multiple languages.

kayakane

// Solution:
// The optimal solution is to use a hash table to store the characters in the string.
// The time complexity of this solution is O(n) where n is the length of the string.
// The space complexity of this solution is O(n) where n is the length of the string.

function isUnique(str) {
  let hash = {};
  for (let i = 0; i < str.length; i++) {
    if (hash[str[i]]) {
      return false;
    }
    hash[str[i]] = true;
  }
  return true;
}

console.log(isUnique("abcdefg"));
console.log(isUnique("aabbcc"));