Given a string s, you are allowed to convert it to a palindrome by adding characters in front of it. Find and return the shortest palindrome you can find by per...

Given a string of numbers and operators, return all possible results from computing all the different possible ways to group numbers and operators. The valid op...

Given a string array words, find the maximum value of length(word[i]) * length(word[j]) where the two words do not share common letters. You may assume that eac...

Given a string that contains only digits 0-9 and a target value, return all possibilities to add binary operators (not unary) +, -, or * between the digits so t...

There are two kinds of threads, oxygen and hydrogen. Your goal is to group these threads to form water molecules. There is a barrier where each thread has to wa...

Given s1, s2, s3, find whether s3 is formed by the interleaving of s1 and s2.

Note: It is intended for the problem statement to be ambiguous. You should gather all requirements up front before implementing one.

The count-and-say sequence is the sequence of integers with the first five terms as following:

Given a digit string, return all possible letter combinations that the number could represent.

String / int(float)/bool / null / object