https://github.com/nikhil22/self-driving-car-collision-courses

Find all collision courses given a N X M matrix representing a road filled with self driving cars
https://github.com/nikhil22/self-driving-car-collision-courses

algorithms es6 es6-javascript javascript javascript-algorithm new self-driving-car webdevelopment

Last synced: 9 months ago
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Find all collision courses given a N X M matrix representing a road filled with self driving cars

• Host: GitHub
• URL: https://github.com/nikhil22/self-driving-car-collision-courses
• Owner: Nikhil22
• Created: 2017-03-15T00:14:48.000Z (over 8 years ago)
• Default Branch: master
• Last Pushed: 2021-08-24T19:34:46.000Z (about 4 years ago)
• Last Synced: 2025-01-08T00:22:58.751Z (11 months ago)
• Topics: algorithms, es6, es6-javascript, javascript, javascript-algorithm, new, self-driving-car, webdevelopment
• Language: JavaScript
• Size: 2.07 MB
• Stars: 2
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

          
# Self Driving Car: Find all collision courses given a N X M grid/array representing a road full of self driving cars

## Problem

Among the many things a self-driving car must consider when driving, the car has to ensure it doesn’t collide with any other cars.

We can represent a road as an N X M grid. How can we tell whether 2 cars are on a collision course with each other?

Take a look at these short animations and see if you notice something.

## Collision

![demo](images/crash.gif)

## Safe

![demo](images/safe.gif)

## Diagonal

The key? Cars that are on a collision course are on the same diagonal. We know this because they are moving at the exact same speed. See the 'Assumptions' section below for more details about this.

![demo](images/diagonal2.png)

## Input

A 2D array, with 1s and 0s



  
1 signifies there is a car at the coordinate

  
0 signifies the coordinate is empty




  [0, 1, 1, 1, 0, 0, 1, 1, 0, 0]

  [1, 1, 1, 1, 1, 0, 0, 1, 1, 1]

  [0, 1, 0, 0, 0, 0, 1, 0, 1, 1]

  [0, 1, 0, 1, 1, 0, 0, 1, 0, 0]

  [1, 1, 0, 0, 0, 1, 1, 0, 1, 1]

  [1, 0, 0, 1, 0, 0, 1, 0, 0, 1]

  [1, 1, 0, 1, 1, 1, 0, 1, 0, 1]

  [1, 0, 0, 0, 0, 0, 0, 0, 1, 0]

  [1, 0, 1, 1, 1, 1, 1, 0, 0, 0]

  [1, 0, 0, 0, 1, 1, 1, 1, 0, 1]



## Output

An Object, with key as stringed coordinates, and value as an an array of coordinates which are collision courses

Example: The collision courses of (0,0) are coordinates (1,1), (3,3) & (9,9) because (1,1), (3,3) & (9,9) are diagonals and have cars in them



  {

    0,0: [[1, 1], [3, 3], [9, 9]],

    0,1: [[1, 2], [3, 4], [4, 5], [5, 6], [6, 7], [7, 8], [1, 0]],

    0,2: [[1, 3], [4, 6], [1, 1]],

    0,3: [[1, 4], [6, 9], [1, 2], [2, 1]],

    .....

  }



## Assumptions

### All cars in the same road are moving at the exact same speed. We make this assumption for 2 reasons



  
They are on the same road space (same speed limits)  

  
They are autonomous (can control the exact speed they go)



## In data structure terms

Given a 2D array, find all diagonals of all coordinates.

## Inspiration

[The Simple Solution To Traffic](https://www.youtube.com/watch?v=iHzzSao6ypE&t=17s)

### Author

Nikhil Bhaskar