A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below).
Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.
Convert a non-negative integer to its english words representation. Given input is guaranteed to be less than 231 - 1.
Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.
Given an input character array, reverse the array word by word. A word is defined as a sequence of non-space characters.
Given a list of non negative integers, arrange them such that they form the largest number.
The count-and-say sequence is the sequence of integers with the first five terms as following:
Given a positive integer, return its corresponding column title as appear in an Excel sheet.
Given a column title as appear in an Excel sheet, return its corresponding column number.
