Great comment on how we can find the shortest path with different endpoints! Gave me a much needed starting point for modifying "Eulerian Cyclic" to find an "Eulerian Path"!
Great video! The last algorithm (where to start and finish) was explained specific to the problem. If you think about graphs that are larger, you will notice that you have to expand the explanation a little to make it truly work. You have to minimize no longer the total, but the total of all pairs except one (which contains start and end). Since in this example "the total of all pairs except one" is just one pair, you are picking the smallest pair which is 3. Just to help understanding the logic behind it :)
When You made the video I was in class 8th and would never imagine that time that this would help me after so many years. Great explanation thank You so much, Man.
@Matthew Jenkinson: What is often considered the first theorem in graph theory was Euler's solution to the Seven Bridges of Königsberg Puzzle. It is based on the simple observation that "The number of odd nodes in a graph is even." To see (or prove?) this, note that each edge has 2 ends, so the sum of the degrees of all nodes (= the total number of edge-ends) is even; since the sum of the degrees of all even nodes must obviously be even, then so must be the sum of the degrees of all odd nodes; but the sum of an odd number of odd numbers can never be even, so there must be an even number of odd nodes. Or, put otherwise, draw me a graph with exactly 3 odd nodes then I'll answer your question...
Cool this was nice, simple, and straight to the point. I didn't learn about algorithms in school and idk. My teacher said we were skipping that unit and we did. Again, idk why. But I was curious as to how these work and I wanted to know how to solve some of them. This was a great example. From watching this I found another way to solve the first question without having to do all the work (although ppl should learn how to do the work lol) But I noticed all you have to do is start at point A, find the shortest path by eye (as you mentioned) then add the path you took. ( now unless you're fully aware of what you're doing I suggest that you learn how to do the work if you don't have a good eye. Because it is trial and error as he mentions. But doing the work would help to double check for the correct answer.) I know this is a lot but that's just what I noticed. I just like finding other ways to do things whether it's simple or complex. Lol, well thanks for this tutorial!! You just gained a new subscriber
The examinations person at my school always says never to use a pencil as it doesnt scan through when the exam boards take the papers in, but i always use pencil when doing djikstras and the gantt diagrams etc in case i make a mistake, any advice on this?
Thankyou! I had no idea what was meant by the pairings and thought they were just pulling the pairs out of their arse 😂 now i know it it seems so simple.
What TheGreenNarwhal said. That is true because an undirected graph with only even-degree vertices is a cycle. Unless it is a tree but hopefully you aren't running such an algorithm on a tree. xD
@MathMathsMathematics I think the task you have written is wrong. "find a route round all points from A with the least cost" should say "find a route round all EDGES from A with the least cost" or am I wrong? But you sad it right.
The number of odd degree vertices has to be even, because sum of all the degrees should be twice the number of edges. Every edge goes out of one node and goes into one node, so every edge counts as an in and an out degree, contributing 2 to the sum of degrees.
Miguel Angel Corona Sandoval Then the Euler path will pass through that node twice unless it's the start of the path--in which case it will both start and end there and pass through it one other time.
He didn't explain why the lines where numbered in the way they were. Why is line 3 , 3, and line 4, 4, etc ? Btw I am not a maths graduate I was just interested in this problem.
Paul L These lines are called edges, Number shown next to the edges is the value or weight of that edge. For example suppose the graph in the video is a road map then distance from Street A to Street B is 1 KM, From B to C is 3 KM, from D to E is 4 KM and so on.
Got my D1 exam in 3 days, forgot how to do this... You're an absolute legend!
Great comment on how we can find the shortest path with different endpoints! Gave me a much needed starting point for modifying "Eulerian Cyclic" to find an "Eulerian Path"!
Great video!
The last algorithm (where to start and finish) was explained specific to the problem. If you think about graphs that are larger, you will notice that you have to expand the explanation a little to make it truly work. You have to minimize no longer the total, but the total of all pairs except one (which contains start and end). Since in this example "the total of all pairs except one" is just one pair, you are picking the smallest pair which is 3.
Just to help understanding the logic behind it :)
Very informative. Clear, simple and to the point. Thanks for the help!
When You made the video I was in class 8th and would never imagine that time that this would help me after so many years. Great explanation thank You so much, Man.
You have no idea how much this has helped me, thankyou!!
konecheewagwarn
Tomasz Whitehead I'm creasing
It means -
Hello, What's going on ?
I don't think this will come up in the exam, but I wish it does. Great explanation, thanks for the video!
@Matthew Jenkinson: What is often considered the first theorem in graph theory was Euler's solution to the Seven Bridges of Königsberg Puzzle. It is based on the simple observation that "The number of odd nodes in a graph is even." To see (or prove?) this, note that each edge has 2 ends, so the sum of the degrees of all nodes (= the total number of edge-ends) is even; since the sum of the degrees of all even nodes must obviously be even, then so must be the sum of the degrees of all odd nodes; but the sum of an odd number of odd numbers can never be even, so there must be an even number of odd nodes. Or, put otherwise, draw me a graph with exactly 3 odd nodes then I'll answer your question...
I used this last year for my exam it is amazing thank you!!!! i got a U though
Cool this was nice, simple, and straight to the point. I didn't learn about algorithms in school and idk. My teacher said we were skipping that unit and we did. Again, idk why. But I was curious as to how these work and I wanted to know how to solve some of them. This was a great example.
From watching this I found another way to solve the first question without having to do all the work (although ppl should learn how to do the work lol)
But I noticed all you have to do is start at point A, find the shortest path by eye (as you mentioned) then add the path you took.
( now unless you're fully aware of what you're doing I suggest that you learn how to do the work if you don't have a good eye. Because it is trial and error as he mentions. But doing the work would help to double check for the correct answer.)
I know this is a lot but that's just what I noticed. I just like finding other ways to do things whether it's simple or complex. Lol, well thanks for this tutorial!! You just gained a new subscriber
what if there is an odd number of vertices with an odd # of edges, how will i do the pairings?
Knew a Japanese Jamaican guy who use to spit bars and start off with KonichiWagwarn
Thank you. Your video really helped me in the exam I just had....
thank you sooo much :O especially on the last bit with the ... starting and finishing at a different place
finally understood how to do that start & finish part :) thank you!
Thanks for the helpful video! Been stuck on homework but i get it now!
MAN TOTALLY LOVE YOU AND THANK YOU SO MUCH
can ds algorithm be apply to ds kind of problem ?how should one to locate ambulance stations so as to best serve the needs of the community?
The examinations person at my school always says never to use a pencil as it doesnt scan through when the exam boards take the papers in, but i always use pencil when doing djikstras and the gantt diagrams etc in case i make a mistake, any advice on this?
thank you so much for this tutorial. it really helped me a lot
Thankyou! I had no idea what was meant by the pairings and thought they were just pulling the pairs out of their arse 😂 now i know it it seems so simple.
This video helped me a lot. Thank you!
is it a eulerian trail
Great tutorial, it helped a lot, thank you :)
that fact you sound like derren brown definitely helps.
what if you have all vertices with even degrees?
the route length is just all the edges added together because you can draw a route without repeating an edge
What TheGreenNarwhal said. That is true because an undirected graph with only even-degree vertices is a cycle. Unless it is a tree but hopefully you aren't running such an algorithm on a tree. xD
wait what, how do you make a tree with only even degree vertices?
MirageOwl what do you mean? Think binary trees, quad-trees, oct-trees, etc.
Leafs in those trees have degree 1. (and for example internal nodes in a binary tree has degee 3 I think, only the root would have even degree)
Hey, i hope this reaches you, could you please make a video on Critical Path Analysis? I really appreciate your videos!!
but, if you go ABCEDA it's worth 13
great video. how would you do chinese postman problems with 6 odd nodes rather than 4?
@MathMathsMathematics
I think the task you have written is wrong. "find a route round all points from A with the least cost" should say "find a route round all EDGES from A with the least cost" or am I wrong? But you sad it right.
which program you said we can use to make this quicker in real life?
What do you do if you've got 3 odd nodes and are trying to pair them? should I write down all the possible combinations or is there a better way?
The number of odd degree vertices has to be even, because sum of all the degrees should be twice the number of edges. Every edge goes out of one node and goes into one node, so every edge counts as an in and an out degree, contributing 2 to the sum of degrees.
Helped me a lot. Thanks
What if you have 4 posibilities in a node?
Miguel Angel Corona Sandoval Then the Euler path will pass through that node twice unless it's the start of the path--in which case it will both start and end there and pass through it one other time.
5:42 down the blow rude
haha !!
THAT VIDEO WAS AMAZING!! could you do a dijkstra video please. I have an exam tomorrow morning and I still dont get it ;/
Thank you very much!
Thank you so much you saved me.
He didn't explain why the lines where numbered in the way they were. Why is line 3 , 3, and line 4, 4, etc ? Btw I am not a maths graduate I was just interested in this problem.
Paul L These lines are called edges, Number shown next to the edges is the value or weight of that edge. For example suppose the graph in the video is a road map then distance from Street A to Street B is 1 KM, From B to C is 3 KM, from D to E is 4 KM and so on.
Raghav Tripathi Thanx, I did go on to find out, but thanx anyway.
thanks for helping me 😁
thank you!!! I have exam today
you deserve subscription, like and comment tooo....that's all i can do for u
Thanks a lot...
helped soo much
i love you
Thanks!
Konnichiwagwan lol
This helped
screech, do it in pencil and go over it in pen when you are sure you're right maybe?
the konichi wagwan killed me in the beginning xd
it's not even chinese man its japanese xdddd Good shit tho
Its 25 not 24
1+2+3+4+5+6+1+2=24
Don't know where you got 25 from
Dumb
Commenting so someone can reply on my comment after 10years...Nostalgia
Are you eating????