Source: Beacon Exclusion Zone

Part 1

There are a collections of Sensors and Beacons. As input, you are given the Beacon closest to each Sensor (using Manhattan Distance). If a Beacon is not closest to any sensor, it will not appear in this list. Calculate how many points in the given row (y=2000000) cannot contain a Beacon.

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Source: Regolith Reservoir

Part 1

Given a series of walls as input, run a falling sand simulation until any new sand falls of the map. Count how many grains of sand we end up with.

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Source: Distress Signal

Part 1

Given pairs of Signals (where a Signal is a nested list ;example: [[1],[2,3,4]]), count how many pairs are ‘in order’.

One Signal is less than the other if:

• Both are an integer and the first is less than the second
• Both are a list and the first value is less than the second
  • If the first values are the same, compare the second
  • If the first has fewer elements, it is treated as less than the second
• When comparing an integer and a list, wrap the integer as a single element list and compare them

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Source: Hill Climbing Algorithm

Part 1

Given a height map, find the shortest path between two points such that the path can descend any distance but can only climb by a maximum of 1.

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Source: Monkey in the Middle

Part 1

Simulate a collection of ‘monkeys’. Each monkey will have a number of items which it will then apply a mathematical operation to, then always divide by 3, then test divisibility to pass to one of two other monkeys. Return as answer the product of the two highest number of times a monkey applies it’s main function to individual items after 20 steps.

Note: Monkeys will always be evaluated in order (so monkey 1 will evaluate any items passed by monkey 0 again in the same round).

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Source: Cathode-Ray Tube

Part 1

Implement a simple virtual machine with two instructions: nop which does nothing for 1 cycles and addx $n which adds $n to the X register (initial value 1) in two cycles. Calculate the sum of cycle * X for the cycles 20, 60, 100, 140, 180, 220.

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Source: Rope Bridge

Part 1

Simulate two connected links such that whenever the first link (head) moves, the tail moves to follow according to the following rules:

• If the tail is at the same location as head, don’t move
• If the tail is adjacent to the head (orthogonal or diagonal), don’t move
• If the tail is in the same row/column as the head, move one directly towards it orthogonally
• If the tail is in neither the same row nor column, move one towards diagonally

Count how many unique spaces are visited by the tail of the link.

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Source: Treetop Tree House

Part 1

Given a grid of numbers, count how many of these numbers have a direct path in any cardinal direction to the edge of the grid.

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Source: No Space Left On Device

Part 1

Give the output of a very simple shell with only the commands cd and ls (the output of which is either "dir" name for directories or size name for files), find the largest directory (disk usage calculated recursively) with a size no greater than 100,000.

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Source: Tuning Trouble

Part 1

Given input as a list of characters, find the index of the first sliding window (size 4) where all of the characters are distinct.

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