1. Arrays and Strings

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• 1.1 Implement an algorithm to determine if a string has all unique characters. What if you can not use additional data structures?
• 1.2 Write code to reverse a C-Style String. (C-String means that “abcd” is represented as five characters, including the null character.)
• 1.3 Given two strings, write a method to decide if one is a permutation of the other
• 1.4 Write a method to replace all spaces in a string with ‘%20’
• 1.5 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.
• 1.6 Given an image represented by an NxN matrix, where each pixel in the image is 4 bytes, write a method to rotate the image by 90 degrees. Can you do this in place?
• 1.7 Write an algorithm such that if an element in an MxN matrix is 0, its entire row and column is set to 0.
• 1.8 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 (i.e., “waterbottle” is a rotation of “erbottlewat”).