Here’s a problem that appeared on Round 1B of Google’s Code Jam 2011 edition: Problem In the United States, 350 schools compete every year for an invitation to the NCAA College Basketball Tournament. With so many schools, how do you decide who should be invited? Most teams never play each other, and some teams have […]
In order to practice for the Round 1 of Google Code Jam 2012, which is coming in two weeks, I started solving the problems of the same round of last year’s edition. Below you’ll find the first one: The Problem I played D (D > 0) games of FreeCell today. Each game of FreeCell ends […]
This problem was worth 20 points, and you needed to think about it a bit, but finding the answer wasn’t that difficult. The Problem You’re watching a show where Googlers (employees of Google) dance, and then each dancer is given a triplet of scores by three judges. Each triplet of scores consists of three integer […]
This weekend the qualification round of Google Code Jam 2012 took place. There were 4 problems, and you need to score at least 20 points to pass to the next round. This first problem was worth 15 points, and it was pretty trivial, so pretty much 15 free points for anyone who tried. The Problem […]
This Saturday the Amazon CodeNinja Programming Contest is taking place. Here’s the first problem: GIven a 2D NxN matrix, visualize it as concentric circles. You have to find the rotated matrix where each element in the circle is rotated by 1 position layer by layer in an alternate clockwise and anticlockwise direction. Input Format: First […]
Suppose you want to find the sum of the squares of all integers from 1 up to 200. Doing it manually would be boring a take a lot of time. Instead you can use the formula below: S = 1/6 * n * (n + 1) * (2n + 1) So in our case the […]
Suppose you have 10 tenis players competing on your tournament, and you want to figure out in how many different pairs you can organize them so that they can play their first match. One way to calculate this is the following: First pick one player at random. Now to pick his opponent you have 9 […]
First make sure to read the basics of permutations. So what’s the different between permutations and combinations? Suppose we have set A = {a,b,c,d,e}. A permutation of that set could be abc, and another permutation could be acb. In other words, a permutation is an arrangement of the objects of set A, where order matters. […]
The oldest known trivial algorithm known: int gdc (int x, int y){ int temp; while (y!=0){ temp=y; y=x%y; x=temp; } return x; } Check the Wikipedia entry to read more about it.
Here’s a cool trick to find the number of divisors of any number easily. First of all find the prime factors of that number. Say we want to do it for 1000. 1000 = 2³ * 5³ Now we can say that all proper divisors of 1000 will be in the form of 2^a * […]