Learn Adjacency Lists in 8 minutes 📑

[@BroCodez]

public class Main { public static void main(String[] args) { // Adjacency List = An array/arraylist of linkedlists. // Each LinkedList has a unique node at the head. // All adjacent neighbors to that node are added to that node's linkedlist // runtime complexity to check an Edge: O(v) // space complexity: O(v + e) Graph graph = new Graph(); graph.addNode(new Node('A')); graph.addNode(new Node('B')); graph.addNode(new Node('C')); graph.addNode(new Node('D')); graph.addNode(new Node('E')); graph.addEdge(0, 1); graph.addEdge(1, 2); graph.addEdge(1, 4); graph.addEdge(2, 3); graph.addEdge(2, 4); graph.addEdge(4, 0); graph.addEdge(4, 2); graph.print(); //System.out.println(graph.checkEdge(0, 1)); } } import java.util.*; public class Graph { ArrayList alist; Graph(){ alist = new ArrayList(); } public void addNode(Node node) { LinkedList currentList = new LinkedList(); currentList.add(node); alist.add(currentList); } public void addEdge(int src, int dst) { LinkedList currentList = alist.get(src); Node dstNode = alist.get(dst).get(0); currentList.add(dstNode); } public boolean checkEdge(int src, int dst) { LinkedList currentList = alist.get(src); Node dstNode = alist.get(dst).get(0); for(Node node : currentList) { if(node == dstNode) { return true; } } return false; } public void print() { for(LinkedList currentList : alist) { for(Node node : currentList) { System.out.print(node.data + " -> "); } System.out.println(); } } } public class Node { char data; Node(char data){ this.data = data; } }

[@masternobody1896]

Thanks

[@masternobody1896]

... What is this

[@joyceasante8292]

Practicing... public class Main { public static void main (String[]args) { Graph graph = new Graph (); graph.addNode (new Node ('1')); graph.addNode (new Node ('2')); graph.addNode (new Node ('3')); graph.addNode (new Node ('4')); graph.addNode (new Node ('5')); graph.addEdge (0, 1); graph.addEdge (1, 2); graph.addEdge (1, 4); graph.addEdge (2, 3); graph.addEdge (2, 4); graph.addEdge (4, 0); graph.addEdge (4, 2); graph.print (); } } ***************************** import java.util.*; public class Graph { ArrayList < LinkedList < Node >> alist; Graph () { alist = new ArrayList (); } public void addNode (Node node) { LinkedList < Node > currentList = new LinkedList (); currentList.add (node); alist.add (currentList); } public void addEdge (int src, int dst) { LinkedList < Node > currentList = alist.get (src); Node dstNode = alist.get (dst).get (0); currentList.add (dstNode); } public boolean checkEdge (int src, int dst) { LinkedList < Node > currentList = alist.get (src); Node dstNode = alist.get (dst).get (0); for (Node node:currentList) { if (node == dstNode) { return true; } } return false; } public void print () { for (LinkedList < Node > currentList:alist) { for (Node node:currentList) { System.out.print (node.data + " -> "); } System.out.println (); } } } ************************ public class Node { char data; Node (char data) { this.data = data; } }

[@pfo9865]

Thank You so much for making these videos, they help me a lot during college :>

[@Snowmanver2]

Thank you for yet another incredible video, Bro!

[@user-zx7bq4lo1g]

Great video man. A video about ortogonal lists would be great

[@mateowang6570]

Thanks for the great vid! Do you have a video explaining adjacency lists for undirected graphs?

[@maruthichowdary8612]

how to add weights for this

[@eduardoignacioroblessosa6349]

as a Node's property

[@sibusisothabethe3109]

A legend 🔥🔥

[@eduardoignacioroblessosa6349]

magnificent

[@juanandresstingo]

Could it be represented in a HashMap? so as Key you put the Node and in Value all the relations for the Node?

[@nikavscode]

Yes, that's another alternative to represent a Graph

[@thalladasriram3936]

can we write LinkedList [ ] ll =new LinkedList() ?

[@RafaelSamuel-f9e]

Great thank you!

[@frazebean5117]

Thank you!!!

[@MrLoser-ks2xn]

Thanks!

[@eugenezuev7349]

a bit tough but still sweet

[@sibusisothabethe3109]

Mine shows null values idk why somebody quickly help

[@willywonka4761]

Miss you, bro

[@keenlearner1891]

same here ... great teacher always leave teaching in between ... broCode if u introduce paid course i will also join but plzz come for us and make full DSA course in java plzzz.... and guide us in becoming great programmer ..............

[@tasneemayham974]

@@keenlearner1891 No, you guys!! Some of us don't have the opportunity to pay. Don't spoil things!! Bro is great and wonderful. Don't turn everything to money. If money grows on your garden trees, donate with them. Don't tell people to change their courses to paid joins.

[@keenlearner1891]

can anyone plzz explain what is NODE ?? why we are passing Node inside generics value ??

[@pt_trainer9244]

It represents the Node of a LinkedList(there is a data part which is the vertex, and a pointer pointing to the next vertex, which is the edge of the graph)

[@tasneemayham974]

We created a class called Node and passed in as arguments char data. We used that as a reference data type. If you hover over Node in your IDE, you see that it points to the class you made called Node, and that if you change the name of the class called Node, you will encounter an error in Graph and Main which means that here Node isn't a data type that is already created. We made it generic when we passed it in as value in the LinkedList. I hope my answer was useful and not too late.