Viral Advertising | Python Solution | HackerRank

 HackerLand Enterprise is adopting a new viral advertising strategy. When they launch a new product, they advertise it to exactly  people on social media.

On the first day, half of those  people (i.e., ) like the advertisement and each shares it with  of their friends. At the beginning of the second day,  people receive the advertisement.

Each day,  of the recipients like the advertisement and will share it with  friends on the following day. Assuming nobody receives the advertisement twice, determine how many people have liked the ad by the end of a given day, beginning with launch day as day .

Beautiful Days at the Movies | Python Solution | HackerRank

 Lily likes to play games with integers. She has created a new game where she determines the difference between a number and its reverse. For instance, given the number , its reverse is . Their difference is . The number  reversed is , and their difference is .

She decides to apply her game to decision making. She will look at a numbered range of days and will only go to a movie on a beautiful day.

Given a range of numbered days,  and a number , determine the number of days in the range that are beautiful. Beautiful numbers are defined as numbers where  is evenly divisible by . If a day's value is a beautiful number, it is a beautiful day. Return the number of beautiful days in the range.

Angry Professor | Python Solution | HackerRank

 A Discrete Mathematics professor has a class of students. Frustrated with their lack of discipline, the professor decides to cancel class if fewer than some number of students are present when class starts. Arrival times go from on time () to arrived late ().

Given the arrival time of each student and a threshhold number of attendees, determine if the class is cancelled.

Example

The first  students arrived on. The last  were late. The threshold is  students, so class will go on. Return YES.

Note: Non-positive arrival times () indicate the student arrived early or on time; positive arrival times () indicate the student arrived  minutes late.