1.1 Is Unique: Implement an algorithm to determine if a string has all unique characters. What if you cannot use additional data structures?
1.2 Check Permutation: Given two strings, write a method to decide if one is a permutation of the other.
1.3 URLify: Write a method to replace all spaces in a string with '%20'. You may assume that the string has sufficient space at the end to hold 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.)
1.4 Palindrome Permutation: Given a string, write a function to check if it is a permutation of a palindrome. A palindrome is a word or phrase that is the same forwards and backwards. A permutation is a rearrangement of letters. The palindrome does not need to be limited to just dictionary words.
1.5 One Away: There are three types of edits that can be performed on strings: insert a character, remove a character and replace a character. Given two strings, write a function to check if they are within one edit of each other.
1.6 String Compression: 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. You can assume the string has only uppercase and lowercase letters (a-z).
1.7 Rotate Matrix: 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?
1.8 Zero Matrix: Write an algorithm such that if an element in an MxN matrix is 0, its entire row and column are set to 0.
1.9 String Rotation: 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 once call to isSubstring
(e.g., "waterbottle
" is a rotation of "erbottlewat
").