google-foobar-challenge
solutions to problems from google foobar challenge
Minion Labor Shifts (problem-1)
Commander Lambda's minions are upset! They're given the worst jobs on the whole space station, and some of them are starting to complain that even those worst jobs are being allocated unfairly. If you can fix this problem, it'll prove your chops to Commander Lambda so you can get promoted!
Minions' tasks are assigned by putting their ID numbers into a list, one time for each day they'll work that task. As shifts are planned well in advance, the lists for each task will contain up to 99 integers. When a minion is scheduled for the same task too many times, they'll complain about it until they're taken off the task completely. Some tasks are worse than others, so the number of scheduled assignments before a minion will refuse to do a task varies depending on the task. You figure you can speed things up by automating the removal of the minions who have been assigned a task too many times before they even get a chance to start complaining.
Write a function called solution(data, n) that takes in a list of less than 100 integers and a number n, and returns that same list but with all of the numbers that occur more than n times removed entirely. The returned list should retain the same ordering as the original list - you don't want to mix up those carefully-planned shift rotations! For instance, if data was [5, 10, 15, 10, 7] and n was 1, solution(data, n) would return the list [5, 15, 7] because 10 occurs twice, and thus was removed from the list entirely.
En Route Salute (problem-2A)
Commander Lambda loves efficiency and hates anything that wastes time. She's a busy lamb, after all! She generously rewards henchmen who identify sources of inefficiency and come up with ways to remove them. You've spotted one such source, and you think solving it will help you build the reputation you need to get promoted.
Every time the Commander's employees pass each other in the hall, each of them must stop and salute each other - one at a time - before resuming their path. A salute is five seconds long, so each exchange of salutes takes a full ten seconds (Commander Lambda's salute is a bit, er, involved). You think that by removing the salute requirement, you could save several collective hours of employee time per day. But first, you need to show her how bad the problem really is.
Write a program that counts how many salutes are exchanged during a typical walk along a hallway. The hall is represented by a string. For example:
"--->-><-><-->-"
Each hallway string will contain three different types of characters: '>', an employee walking to the right; '<', an employee walking to the left; and '-', an empty space. Every employee walks at the same speed either to right or to the left, according to their direction. Whenever two employees cross, each of them salutes the other. They then continue walking until they reach the end, finally leaving the hallway. In the above example, they salute 10 times.
Write a function solution(s) which takes a string representing employees walking along a hallway and returns the number of times the employees will salute. s will contain at least 1 and at most 100 characters, each one of -, >, or <.
Elevator Maintenance (problem-2B)
You've been assigned the onerous task of elevator maintenance - ugh! It wouldn't be so bad, except that all the elevator documentation has been lying in a disorganized pile at the bottom of a filing cabinet for years, and you don't even know what elevator version numbers you'll be working on.
Elevator versions are represented by a series of numbers, divided up into major, minor and revision integers. New versions of an elevator increase the major number, e.g. 1, 2, 3, and so on. When new features are added to an elevator without being a complete new version, a second number named "minor" can be used to represent those new additions, e.g. 1.0, 1.1, 1.2, etc. Small fixes or maintenance work can be represented by a third number named "revision", e.g. 1.1.1, 1.1.2, 1.2.0, and so on. The number zero can be used as a major for pre-release versions of elevators, e.g. 0.1, 0.5, 0.9.2, etc (Commander Lambda is careful to always beta test her new technology, with her loyal henchmen as subjects!).
Given a list of elevator versions represented as strings, write a function solution(l) that returns the same list sorted in ascending order by major, minor, and revision number so that you can identify the current elevator version. The versions in list l will always contain major numbers, but minor and revision numbers are optional. If the version contains a revision number, then it will also have a minor number.
For example, given the list l as ["1.1.2", "1.0", "1.3.3", "1.0.12", "1.0.2"], the function solution(l) would return the list ["1.0", "1.0.2", "1.0.12", "1.1.2", "1.3.3"]. If two or more versions are equivalent but one version contains more numbers than the others, then these versions must be sorted ascending based on how many numbers they have, e.g ["1", "1.0", "1.0.0"]. The number of elements in the list l will be at least 1 and will not exceed 100.
Bomb, Baby! (problem-3A)
You're so close to destroying the LAMBCHOP doomsday device you can taste it! But in order to do so, you need to deploy special self-replicating bombs designed for you by the brightest scientists on Bunny Planet. There are two types: Mach bombs (M) and Facula bombs (F). The bombs, once released into the LAMBCHOP's inner workings, will automatically deploy to all the strategic points you've identified and destroy them at the same time.
But there's a few catches. First, the bombs self-replicate via one of two distinct processes: Every Mach bomb retrieves a sync unit from a Facula bomb; for every Mach bomb, a Facula bomb is created; Every Facula bomb spontaneously creates a Mach bomb.
For example, if you had 3 Mach bombs and 2 Facula bombs, they could either produce 3 Mach bombs and 5 Facula bombs, or 5 Mach bombs and 2 Facula bombs. The replication process can be changed each cycle.
Second, you need to ensure that you have exactly the right number of Mach and Facula bombs to destroy the LAMBCHOP device. Too few, and the device might survive. Too many, and you might overload the mass capacitors and create a singularity at the heart of the space station - not good!
And finally, you were only able to smuggle one of each type of bomb - one Mach, one Facula - aboard the ship when you arrived, so that's all you have to start with. (Thus it may be impossible to deploy the bombs to destroy the LAMBCHOP, but that's not going to stop you from trying!)
You need to know how many replication cycles (generations) it will take to generate the correct amount of bombs to destroy the LAMBCHOP. Write a function solution(M, F) where M and F are the number of Mach and Facula bombs needed. Return the fewest number of generations (as a string) that need to pass before you'll have the exact number of bombs necessary to destroy the LAMBCHOP, or the string "impossible" if this can't be done! M and F will be string representations of positive integers no larger than 10^50. For example, if M = "2" and F = "1", one generation would need to pass, so the solution would be "1". However, if M = "2" and F = "4", it would not be possible.
The Grandest Staircase Of Them All (problem-3B)
With her LAMBCHOP doomsday device finished, Commander Lambda is preparing for her debut on the galactic stage - but in order to make a grand entrance, she needs a grand staircase! As her personal assistant, you've been tasked with figuring out how to build the best staircase EVER.
Lambda has given you an overview of the types of bricks available, plus a budget. You can buy different amounts of the different types of bricks (for example, 3 little pink bricks, or 5 blue lace bricks). Commander Lambda wants to know how many different types of staircases can be built with each amount of bricks, so she can pick the one with the most options.
Each type of staircase should consist of 2 or more steps. No two steps are allowed to be at the same height - each step must be lower than the previous one. All steps must contain at least one brick. A step's height is classified as the total amount of bricks that make up that step.
For example, when N = 3, you have only 1 choice of how to build the staircase, with the first step having a height of 2 and the second step having a height of 1: (# indicates a brick)
#
##
21
When N = 4, you still only have 1 staircase choice:
#
#
##
31
But when N = 5, there are two ways you can build a staircase from the given bricks. The two staircases can have heights (4, 1) or (3, 2), as shown below:
#
#
#
##
41
#
##
##
32
Write a function called solution(n) that takes a positive integer n and returns the number of different staircases that can be built from exactly n bricks. n will always be at least 3 (so you can have a staircase at all), but no more than 200, because Commander Lambda's not made of money!
Prepare The Bunnies' Escape (problem-3C)
You're awfully close to destroying the LAMBCHOP doomsday device and freeing Commander Lambda's bunny prisoners, but once they're free of the prison blocks, the bunnies are going to need to escape Lambda's space station via the escape pods as quickly as possible. Unfortunately, the halls of the space station are a maze of corridors and dead ends that will be a deathtrap for the escaping bunnies. Fortunately, Commander Lambda has put you in charge of a remodeling project that will give you the opportunity to make things a little easier for the bunnies. Unfortunately (again), you can't just remove all obstacles between the bunnies and the escape pods - at most you can remove one wall per escape pod path, both to maintain structural integrity of the station and to avoid arousing Commander Lambda's suspicions.
You have maps of parts of the space station, each starting at a prison exit and ending at the door to an escape pod. The map is represented as a matrix of 0s and 1s, where 0s are passable space and 1s are impassable walls. The door out of the prison is at the top left (0,0) and the door into an escape pod is at the bottom right (w-1,h-1).
Write a function solution(map) that generates the length of the shortest path from the prison door to the escape pod, where you are allowed to remove one wall as part of your remodeling plans. The path length is the total number of nodes you pass through, counting both the entrance and exit nodes. The starting and ending positions are always passable (0). The map will always be solvable, though you may or may not need to remove a wall. The height and width of the map can be from 2 to 20. Moves can only be made in cardinal directions; no diagonal moves are allowed.