[CC150] Chapter 1 Arrays and Strings

5th Edition

1.1 Implement an algorithm to determine if a string has all unique characters. What if you cannot use additional data structures?

Check here.

1.2 Implement a function void reverse(char * str) in C/C++ which reverses a null-terminated string.

Check here.

1.3 Given two strings, write a method to decide if one is a permutation of the other.

Check here.

1.4 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.

Check here.

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?

This problem is in leetcode as Rotate Image. My previous solution is here.

1.7 Write an algorithm such that if an element in an MxN matrix is 0, its entire row and column are set to 0. 

This problem is in leetcode as Set Matrix Zeroes. My previous solution is here.

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.

 If s1 is a rotation of s2, then s1 can be divided to x + y, and s2 can be divided to y + x. Note that yx is always a substring of xyxy.

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