This Easter Bunny HQ node app computes the location of Easter Bunny Headquarters (EBHQ) on a city grid from a given sequence of (meandering) directions through the city grid. The city grid is represented as a fixed Cartesian coordinate system. Using the EBHQ coordinates, the Manhattan distance--the shortest path in number of city blocks--between the starting point [0,0] and EBHQ is then computed and reported.
- Mac OS X El Capitan version 10.11.6 (15G1217).
- Node v6.0.0
- npm module make-runnable is used to run exported functions via the npm scripts commands
- Install node if necessary
- Clone or download this repo
- In your terminal,
cdto the root directory and run:npm install - To run the app with the given (hardcoded) input:
npm run goBunny - The minimum number of blocks one could travel to reach Easter Bunny HQ is reported in your terminal.
Run the EBHQ App tests with the example data provided by Advent of Code: npm test
This repo contains a vanilla javascript node app that solves the 2016 Advent of Code Day 1 problem. In summary, one must traverse a specific path on a city grid to locate the Easter Bunny Headquarters. A path to HQ is provided in a sequence of instructions of the form R1, L3, L2, meaning go right one block, then go left three blocks, then go left two blocks. Given the restriction that one can only traverse along the city blocks (one cannot travel as the crow flies) the task is to find the shortest Manhattan distance in city blocks from the starting point to the EBHQ. It is assumed that the given path is a meandering path, perhaps a scenic tour of the city, and not the shortest distance.
In my code Dr. Bunny is dropped into the city and finds the Easter Bunny HQ by 'theoretically' traversing the grid according to the provided input sequence. Once the EBHQ position is located, the minimum number of blocks that Dr. Bunny could hop along to get to EBHQ is computed.
The input from Advent of Code is a sequence of instructions such as R5, L5, R5, R3 that are fed into the program as an array of strings ['R5', 'L5', 'R5', 'R3']. The app parses each string into turn direction and distance to travel in the form {turn: 'R', distance: 5}.
The starting point is assumed to be [0,0] on the Cartesian grid and all blocks are assumed to be equidistant squares. The problem states Dr. Bunny is facing north when dropped into the city grid.
Expressed as direction vectors on a Cartesian grid, the four cardinal directions are grouped in an array representing the clockwise rotation from North to West : var cardinalDirectionVectors = [[0,1],[1,0],[0,-1],[-1,0]]. A 90 degree right turn is a clockwise turn and a 90 degree left turn is counterclockwise turn and thus the change in direction vector can be determined incrementing or decrementing the array index. (An increment at index 3 goes to index 0, and a decrement at index 0 goes to index 3.)
Once the new direction vector is determined from the turn instruction, the distance to walk/hop/travel is multiplied by the direction vector to compute the distance moved in either the x or y direction. This distance is added is added to the current [x,y] position. This repeats through each of the input sequence instructions. The final [x,y] coordinates reveal the location of the EBHQ. Using the EBHQ coordinates and the [0,0] start coordinates the minimum number of blocks to get to HQ is computed as the sum of the absolute value of the x coordinate and the y coordinate.
The node app will print the minimum number of blocks in the terminal window as:
Dr. Bunny could get from her start point to Easter Bunny HQ in a mere 301 blocks.
Input Sequence: [ 'R2', 'R2', 'R2' ]
Output Minimum Blocks: Dr. Bunny could get from her start point to Easter Bunny HQ in a mere 2 blocks.
This project is licensed under the MIT License - see the LICENSE.md file for details
I have often used TasteJS's todomvc repo and Howard Tang's giraffeMaker repo as guides for structuring vanilla javascript apps. You will see the patterns from the giraffeMaker pseudoClassical approach in this app.
References for a good README http://blog.lookahead.com.au/post/98298040306 https://gist.github.com/PurpleBooth/109311bb0361f32d87a2