Given an integer, write a function to determine if it is a power of two.
Reverse digits of an integer. Return 0 when the reversed integer overflows.
Given two binary strings, return their sum (also a binary string).
Given a non-negative number represented as an array of digits, plus one to the number.
Write a function that takes an unsigned integer and returns the number of ’1' bits it has.
Given a non-negative integer num, repeatedly add all its digits until the result has only one digit.
Given an integer, convert it to a roman numeral.
Given a roman numeral, convert it to an integer.
Write an algorithm to determine if a number is "happy".
Given two numbers represented as strings, return multiplication of the numbers as a string.
Find the total area covered by two rectilinear rectangles in a 2D plane.
Implement a basic calculator to evaluate a simple expression string.
Implement a basic calculator to evaluate a simple expression string with '+','-','*','/'.
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.
Given two integers representing the numerator and denominator of a fraction, return the fraction in string format. If the fractional [...]
Count the number of prime numbers less than a non-negative number, n.
Write a program to check whether a given number is an ugly number.
Write a program to find the n-th ugly number.
Implement atoi to convert a string to an integer.
Determine whether an integer is a palindrome. Do this without extra space.
Determine if you could win a Nim Game
Given an integer n, return the number of trailing zeroes in n!.