Write an algorithm to determine if a number is “happy”.

Reverse bits of a given 32 bits unsigned integer.

Write a function that takes an unsigned integer and returns the number of ‘1’ bits it has (also known as the Hamming weight).

Write a SQL query to rank scores. If there is a tie between two scores, both should have the same ranking. Note that after a tie, the next ranking number should...

Given a list of non negative integers, arrange them such that they form the largest number.

Given an unsorted array, find the maximum difference between the successive elements in its sorted form.

Given a positive integer, return its corresponding column title as appear in an Excel sheet.

Given an integer n, return the number of trailing zeroes in n!.

Evaluate the value of an arithmetic expression in Reverse Polish Notation.

Given an integer array nums, find the contiguous subarray within an array (containing at least one number) which has the largest product.