Strings

1. Implement an algorithm to determine if a string has all unique characters. What if you cannot use addtional data structures?
2. How to reverse a string in c?
3. Given two strings, write a method to decide if one is a permutation of the other? isAnagram
4. Write a method to replace all spaces in a string with '%20'.

• You may assume that the string has sufficient space at the end of the string to hold the additional characters,
• and that you are given the "true" length of the string. (Note: if implementing in java, please use a character array so that you can perform this operation in place.)

5. Implement a method to perform basic string compression using the counts of repeated characters. For example, the string aabcccccaaa would become a2b1c5a3.

• If the "compressed" string would not become smaller than the original string, your method should return the original string.

6. Assume you have a method isSubstring which checks if one word is a substring of another. Given two strings, s1 and s2, write code to check if s2 is a rotation of s1 using only one call to isSubstring (e.g., "waterbottle" is a rotation of "erbottlewat").
7. Given a string, find the first non-repeating character in it and return it's index. If it doesn't exist, return -1. FindTheFirstNonRepetitiveChar
8. Given a string, find the length of the longest substring without repeating characters. longest-substring-without-repeating-characters

Questions 1-6 have been taken from Cracking the Coding Interview