Coding Challenge #35.1: Traveling Salesperson

[@neomage2021]

As a software engineer I enjoy watching these videos. I find them relaxing. You are really good at teaching. Keep up the good work!

[@TheCodingTrain]

That's so nice to hear thank you!

[@insidioso4304]

Derick Hess Me too! Actually it is relaxing but at the same time it makes you feel the need to code! I would call this new way of relaxing: "prograxing"

[@ericowens9050]

Derick Hess Same here. Makes me feel better to not be alone in that feeling. :-)

[@Pradeep.Poonia]

@@TheCodingTrain Does Derick look like the guy who wrote this paper : kzbin.info/www/bejne/naC4naymadeqn7c @DerickHess

[@amandixit3555]

@@TheCodingTrain choo choo , abey bada ho ja bhai. choo choo

[@clementbuchanan587]

Seriously Dan, I luv, luv, luuuv the way you teach. I am a software developer in training and you make it so much more palatable to digest. I truly hope you continue this great work you're doing man. You're my go to resource when I need ANYTHING for coding.

[@kevnar]

I took the formula for line intersection from your Ray Casting video and I just made the TSP algorithm swap the tails of two random intersecting lines in the path. Then I gave it 999 points, and it unscrambled the path in a matter of ten minutes or so. It's not the shortest path, but the amount of progress for that many points is amazing.

[@tiffsea8876]

I love that you chose to use 'salesperson' as opposed to traditional 'salesman' term - obviously not all sales persons are 'men'. Thank you for thinking at that level! Makes a huge difference for mental processing!

[@DodaGarcia]

1:10: "Oh a Pokémon Go analogy, this will be easy to follow!" 1:15: "N-dimensional? I'm lost"

[@jhokeypokey]

I come from the future to let you know that this is still interesting.

[@pretzels3273]

Jared Fairchild and Pokémon go is relevant again

[@Seedx]

Welp it’s 2020

[@t__v_____290]

Not anymore buddy

[@bechirjamousi6696]

TSP needs to get back to its initial position and in this case, it is not , am i right?

[@jetison333]

Further in the future here, can confirm its still interesting

[@Lehiannel]

Perfect! I am studying it for a project in my R coding class. Your logic explanation was clear, didatic and easy to understand. I enjoyed it :) Keep making videos like that!

[@nataliekidd2135]

I really love these videos, they are super informative. I'm a Sophomore in college earning my degree in Computer Science. Even though I haven't learned Java or JavaScript, I really appreciate these videos.

[@bikachu_]

you're a great teacher and thanks for being so enthusiastic about programming, it really keeps me going!

[@manurok1901]

Love these videos! Been binge watching while I'm off work the past couple of days :p Keep it up man, you're inspiring

[@sherhy3689]

patient, adequately funny, and informative, please continue this as long as you can --tokyo

[@golfball_diver]

i know this is late, but i think the travelling salesman problem requires you to go back to your starting location after visiting every city.

[@alirizvi710]

yeah otherwise its just a minimum spanning tree problem

[@themanwiththeplan8404]

isn't that a hamilton cycle?

[@VizGhar]

TSP is shortest hamiltonian cycle yes

[@nowar9220]

first channel ive ever subscribed to!! Really worth it :) Thanks! Apreciate it!!

[@mihaitmf]

Man, that's awesome! So simple, yet so neat.

[@Hyuts]

I finally downloaded processing! Very cool and easy to install plus allows me to follow along and use all github projects. Thanks!

[@ronraisch510]

I yelled "SUM!!!" at the screen for like 4 min lol

[@sina-qh8wm]

I created a presentation in university based on this video, thanks a lot :)

[@nraynaud]

I used a traveling salesman in a CNC application, when milling a bunch of pockets, to choose the order of the pockets.

[@omshrisn2909]

I like your approach of programming!!! , understood more clearly than what teachers teach in my college thanks 😃

[@TheDogn]

7:13 The bell was a hilariously unexpected touch.

[@per1sher]

Fascinating video - always enjoy your channel - your enthusiasm is infectious :)

[@heavencanceller1863]

These videos are both priceless information and entertainment

[@Ensii]

Your enthusiasm is priceless :) nice video

[@TheCodingTrain]

Thank you!

[@seanhudson8453]

Came here for my uni course. Stayed for the flamboyancy

[@LorenzoLeonardini]

"What are the things in your world that you need to find the path way through?" everything in my room I guess

[@amateuraaron6972]

Hey Dan! Just wanted to say its 2022 about 6 years later Pokemon Go is still relevant enough for this video hahaha

[@anonymousvevo8697]

i come from 2020 and your video is still awsome

[@kevnar]

Sally has 12 boyfriends. In order to keep them from finding out about each other, she insists on having her visits at the guy's houses. What route does she visit them in that saves her the most travel time so she can maximize the time she spends with each guy?

[@MrCmon113]

Damn, Sally is even worse than Chuck, who's always trying to spy on Alice and Bob.

[@Violet-tb8xo]

@@MrCmon113 eve?

[@kyokarson8233]

@@MrCmon113 we used to have Darth spying on alice and bob when the love birds wanted to talked :p

[@arumifitria5433]

Thanks u inspired me a lot

[@kavinbharathi]

_why? Just why?_

[@glenneric1]

I think one way of avoiding the trap that you see at 21:18 is to sometimes swap more than 2 points. Though that actually isn't a two point trap now that I look at it.

[@sairamankilambi5007]

2020 it is! Travelling back in time to understand Travelling Sales Person problem...

[@Nerdthagoras]

I plan to use this to find the optimal route while shopping for various items at Walmart!

[@TheCodingTrain]

Haha, look forward to hearing how that goes!

[@Thijs-Kuiken]

What this video needs is.... more talking with the arms and hands. ;-) interesting stuff! though a lot flies over my head. You're an enthusiastic teacher.. fun watch.

[@amit_awadhi]

It should be renamed to "Catching-Pokemon-Problem"😂👌

[@davidstephen2219]

Simple and easy as always. Keep go on. I wish I was one of your students in your class. );

[@rafageist]

If you don't have the restriction of returning to the starting city, then you have leftover combinations. A B C would be the same as C B A, and so on.

[@omaryahia]

your videos are amazing, thank you Daniel

[@luiginotcool]

Hey I’m from the future and this is actually really useful for solving shwolobatata-hmm problems

[@memporium240]

You can actually reach an upper bound of n^2*2^n which is a better bound than n factorial.

[@sujals7108]

instead of writing 'bestEver = cities.slice();', you can just write 'bestEver = cities;'. It copies the array exactly

[@rankail]

He did it that way first and then "corrected" it. XD

[@aryamankejriwal5959]

For the latest thing, the points would be shops where the Nintendo switch is possibly present...

[@RetroGamingClashOfClans]

traveling salesman problem is one of the hardest problem in math having no exact method/equation for finding the EXACT shortest route and its is one of the NP problems.... if you can find a quick way to solve this problem for any number of points, it will proof that P = NP and that will get you million dollars as it is one of the 1million$ millennium problem

[@tythedev9582]

I am a simple man. I see your videos in my recommendations. I watch. LMBO @16:11 "shmoley-patat-in"?

[@aryamankejriwal5959]

22:21 The bell makes a sound, or you might understand it better as follows: class Bell{ static void makeSound(){ System.out.println("Ding"); } }

[@josbex1684]

Interesante gracias... aplicare ahora la heuristica anneling para calcular mas rápido la ruta mas corta

[@deathvall3y]

Energetic.... and lots of love for you

[@exorcistgg9833]

lol I was trying to design a program that calculate the shortest distance to go to all pokestop😂 And then I found your vid

[@quicksanddiver]

Pokemon Go was actually the real reason I got interested in this problem... ^^'

[@cesarrios3449]

Where are u programming this? Are you using an text editor or something else? I would appreciate so much if u can answer me. Excelent video, greetings from Mexico :)

[@TheCodingTrain]

Try some of these workflow videos! (let me know if they are helpful) sublime text: kzbin.info/www/bejne/i3Srq5-Lnql3Z5I atom editor: kzbin.info/www/bejne/mmSylHmbrcpsf80 brackets: kzbin.info/www/bejne/pJ69k5uDltOJmbs codepen: kzbin.info/www/bejne/a5jJhpqEpbhpobs

[@MikaelWallgren]

About 3:00, shouldn't it be n!/2? ABC and CBA is the same path but reversed? I like your videos, keep up the good work!

[@BradHouser]

And so are ACB, BAC, BCA, and CAB. WIth three cities all paths are the same! You must return to the starting city.)

[@ruyuehong2392]

The dynamic network graph is amazing. I wonder how to create those dynamic animation. Is it a special drawing software or particular packages of some languages?

[@DodaGarcia]

I know this is 4 years ago, but just in case you didn't find it, this is p5js! It's a free JavaScript library that makes it easy to create these drawings, and it also has an in-browser editor you can use to get started. It's a fantastic tool and this channel has lots of tutorials for it.

[@michaellazar9078]

does the salesman have to end up at home after hitting each point once or does he travel from job to job forever? #2 if you had a short repeatable solution. how would a person responsibly disseminate their findings?

[@ErikHarloff]

You spoke about providing the Processing code to this example as well. Unfortunately, I didn't find is on github (github.com/CodingRainbow/Rainbow-Code/tree/master/challenges/CC_35_TSP/CC_35.1_TSP). Would you be so nice to provide the Processing code for TSP? Awesome!

[@Teth47]

So it turns out Windows 10's calculator can handle some pretty big numbers, 3000! is ~4.19^9130. Not bad.

[@lumschente]

My Android calculators max is 13547! = 1.085^50089

[@Tuberex]

4,1493596034378540855568670930866 with 9130 zeros

[@Tuberex]

@@lumschente the biggest on windows 10 is 3248

[@Gegellibu]

For the different path calculations the formula is actually n!/2 as ABC is the same path as CBA

[@vernonalbayeros4719]

Still, since when talking about time and space complexities we are referring to very large N counts, the problem's upper bound is still called n! or factorial, since any constant (in your comment's case = (1/2) * n! ) multiplying the n is "irrelevant"

[@unchaynd7266]

5:29 I am here because I'm trying to make a program that can come up with the optimal arrangement for a bunch of chunks of music to form a song, such that the arrangement follows some given rules (e.g., what chunks are allowed to follow what other chunks, minimal repetition of chunks)

[@jschoete3430]

Hi ! Can I ask what studies you did, and what kind of work you do? I'm myself studying IT, and I love these videos and I would like to code like this all day long. also if it's not too much to ask, how much do you make with your job? I know it's a bit of a taboo question, so feel free to ignore ^^

[@joonsungkim1218]

don't you need to return to the starting point?

[@kevnar]

No. The salesman left his wife and family and never plans to go back.

[@Caleb-zj9xi]

That’s called something else.

[@Matt-yp7io]

@@Caleb-zj9xi no its not

[@izoumashka]

well you can narrow down possible paths by just working out which are "edge" vertices and starting from them.

[@nickgooch6928]

You should use something like this to solve the Maze Generator you made ; )

[@gunot5656]

this guy is incredibly entertaining, lol

[@Mosch822]

Great Video. Wanna see more

[@kaal_bhairav_24]

The time complexity can be reduces from n! to (n-1)! since we can fix a point and permute the remaining (n-1) points.

[@BradHouser]

And assuming the distance from A to B equals the distance from B to A, you can divide (n-1)! by 2.

[@gadeichhorn]

great stuff! would like to see ant colony simulation for the same problem or event multiple sales doing each multiple visits.

[@MajorMandyKitten]

I'm in the middle of the video, so I'm not sure if you clarified the actual definition of "shallow copy". A shallow copy is a copy of a variable or array of variables that point to the same address in memory, thus, if you change a value of the original, you change the value of the copy. conversely, a deep copy will actually copy the original to a new address in memory, and allows you to change one of the variables without changing the other.

[@TheCodingTrain]

Thanks for this info!

[@MajorMandyKitten]

The Coding Train this channel is pretty cool! Keep up the good work!

[@epicmonckey25001]

Noob here, what does the index.html file look like. I have it, but when i try to open it in my browser all i get is a black box. PLZ HELP!

[@pqazx1]

how to take input from user for the dist bw points ??and then do this??

[@assimez-zaky8363]

This is relaxing

[@stephfong4577]

Wow, I hope I knew about your channel earlier!

[@yerkoantonioalvarez]

Great video! But tsp requires to return to initial citie

[@Anticitizen666]

Is this a case where a genetic algorithm could do a "good enough" job in a much shorter time for large lists of coordinates? I.e.you could feed it an acceptable total distance, or time to travel, and it could quickly evolve a decent route.

[@tiborsaas]

yes :)

[@vernonalbayeros4719]

I don't know about that. I just finished doing a branch&bound implementation of the traveling salesman problem and I can't see why you'd go the genetic algorithm path on this one (for anyone interested, look up my github and I've done 3 different branch and bound implementations for different heuristics: github.com/drkztan/javasalesman). I've also used dijkstra's algorithm to create some tables to fetch distance data in linear time instead of calculating it at every solution node. Neural network or a very well thought out heuristic+preparation work for a branch and bound type algorithm seems much, much better.

[@TheHpsh]

think something someone can try, is instead of making each gene to be just one city, and mutation changes that city, they can try to make a gene to start with every city, and randomly let every agent select randomly between the possibilities in the gene, and make mutation randomly delete a city in that gene. in a way, this will be the reverse way most genetic algorithm work the idea is that wrong a wrong city in gene x, will make that gene less fit, then a gene without that city. hope that make some sense, english is not my language

[@oooBASTIooo]

Probably not, unless your approximation is really coarse. A property of NP-hard problems is that they cannot be approximated very well. This is because a good approximation yields a precise solution (follows from the PCP theorem, if you want to look it up)

[@TheHpsh]

maybe, one thing i am pretty sure of, is that my code will be very slow :-) partly because of it can't use crossover, and has to have a mutation rate that are extremely low.

[@jeremysmothers4260]

Favorite part: 22:52. "Shruntinpatatadahmmm.... *DING"

[@jeremysmothers4260]

16:51*

[@Tin98Tin]

Please do more in Processing!

[@satishkpradhan]

I work with TSP problems with capacity, multiple time windows, service times and profit. The problem escalates so much faster but with some smart meta heuristics, you can get a nice solution really quick. If someone wants the state-of-the-art method message me... My current best is 100 nodes optimality for simpler problems with 1 vehicle .... Generally improving and check of a route of 20-30 points with time, capacity and profit take less than a millisecond.... so you can try 1000's improvements each second.

[@toshb1384]

"in the future, *some many years from now*, people will be complaining about how pokemon go is irrelevant." LOL, pokemon go has become irrelevant literally after a few weeks

[@mintyplays4682]

Not anymore! It used a Max Revive and brought generation 2 out! :D

[@ryuuji159]

and... stil irrelevant

[@arddison3894]

and... now i actually had forgotten it ever existed.

[@KnakuanaRka]

I think it took a few months, but yeah, it blew over pretty fast.

[@nufik8097]

It's gone

[@Habbxor]

Would Prim's algorithm work better? I searched up and this is an O(V^2), and Prim's is O(|E| log |V|). (V = vertex, E = edge/path b/w points)

[@stoobertb]

Prim's is slightly different. Prim's will give you the Minimum Spanning Tree, which will be the shortest path that connects all cities to at least one other city, however, it may not be the shortest when traversing all cities as you may have to double back on yourself. Think of Prim's as a way of connecting all cities so all cities can be traversed using the least amount of road, however traversing that road may not be the shortest route as going directly.

[@Habbxor]

You're right. Prim's could lead to having to travel the same path again because it doesn't guarantee a linear path.

[@-rXr-]

Hi denial, love your vids, can you make a video on A* path finding algorithm plz

[@makarandlahane3904]

as you said we want the total sum of all distances,then why haven't you returned the sum from calcDistance function?

[@garmurinn]

I think you forgot to put console.log(recordDistance); between line 69 and line 70 in #35.3 in the web editor on the website.

[@MuhammadAfzal-tk9xl]

You explain very well But i have a question on another day i was watching your A* search algorithm video whats the difference between this concept and that A* search ? Secondly can i make code of this in c++? Please do reply

[@satishkpradhan]

A* is for calculating the shortest distance between a node pair... but for tsp, it is tour that starts and end at the same node. That makes the problem hard and can't be solved by exact methods.

[@dibibob1474]

smart and helpful. thanks sir :)

[@Invenitive]

Why did you do linear paths instead of round trips? All of the examples I've seen of the TSP use round trips

[@kevnar]

Scwalla Vatatan! The next new thing! I'm going to create it, just to prove Shiffman right!

[@amit_awadhi]

This video gives me confidence😂 You're exactly like me, always trying to do things bruteforce way till they work fine🤟

[@WahranRai]

Why not computing greedy algorithm (visiting the closest city...) giving you the upper bound ?

[@netbotcl586]

because we want the optimal answer.

[@louis1001]

Starting 2017 and people already finds old Pokémon GO :/ Great Video!!

[@codycodes7527]

this will be remade with you being an imposter and finding how to kill crewmates

[@irfankarmali4849]

Wouldn't using a algorithm be better than using a randomizer or trying every possibilty. Like maybe the Greedy Algorithm or the Bellman-Ford Algorithm.

[@bhavyabhatia2337]

Is there a video for this solution using DP, not brute force ?

[@sudhamahajan2272]

how do u make that animation part??what do u use??

[@rodneyjohnson9476]

I want to use this algorithm but where can I find the listing that explains the Java functions in basic command set

[@coenraadloubser5768]

Array sorting method is going to miss instances where a return trip to a city is shorter than a connecting trip...

[@_rlb]

True, but the salesperson problem specifically states that every city has to be visited exactly once.

[@sudhamahajan2272]

How to stop this prog after iterations are completed..?

[@wardiofficial6945]

could you please make a video to code a system that use GA for navigating the customer of supermarket when they are doing their grocery shopping task. The system should use the shelf's coordinate and the result will display a list of shelf label of the selected shelf from the distance calculated from the supermarket front door. tq

[@chopper3lw]

TSP is the minimum CIRCUITAL path through the points IT IS NOT the minimum path through the set. It's only the CIRCUITAL part that makes it NP-HARD. There's non NP solutions to minimum path.

[@arhabersham]

Help! At 10:05 , I don't see index (element?) [3]... I only see [0] to [2] . Did I miss something?

[@sensei0101]

Isn't it a good idea to cache parts of the system? So when it hits again, it is just to look it up instead of calculating everything all the time?

[@davatron5000]

👍🏻 for "schmullivatatani"

[@emmahii]

There's no way, recalculating the distance between ALL points every time the order changes is in any way efficient... Calculating the distance between every pair of points just once and then just adding them up is much faster.

[@xiandongzhang5927]

You only need to store direct distance between one city and another, so , it's n*(n-1)*0.5

[@DBear8008]

Watching in 2021, PokemonGo is not quite irrelevant but in the back of many peoples minds

[@JustSomebody-e9h]

What library would be good to use in Python to take care of drawing the lines and visually representing this algorithm?

[@funxiobolic]

Check out pyGame. It's a Python library aimed at game developers, so it has a lot of drawing/graphics functions.