[Interview] Check if String has Unique Characters Implement an algorithm to determine if a string has all unique characters What if you can not use additional data structure? package com.Array_Strings; /** * @Question: 1-1. Implement an algorithm to determine if a string has all * unique characters What if you can not use additional data * structure? */ public class Ans1_1 { public boolean helper(String str) { boolean[] map = new boolean[256]; for (int i = 0; i < str.length(); i++) { int val = str.charAt(i); if (map[val]) return false; map[val] = true; } return true; } } Complexity Analysis: Time Complexity: \(O(n)\) Space Complexity: \(O(n)\) Here is my Video Explanation