[Interview] Check if String has Unique Characters

[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: \(O(n)\)

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