Learn Adjacency Matrix in 10 minutes ⬜

adjacency matrix data structures and algorithms tutorial example explained java
#adjacency #matrix #tutorial

[@BroCodez]

public class Main {
public static void main(String[] args) {

// Adjacency Matrix = An array to store 1's/0's to represent edges
// # of rows = # of unique nodes
// # of columns = # of unique nodes

// runtime complexity to check an Edge: O(1)
// space complexity: O(v^2)

Graph graph = new Graph(5);

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); // I forgot this line in the video
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.ArrayList;
public class Graph {
ArrayList nodes;
int[][] matrix;

Graph(int size){
nodes = new ArrayList();
matrix = new int[size][size];
}

public void addNode(Node node) {
nodes.add(node);
}

public void addEdge(int src, int dst) {
matrix[src][dst] = 1;
}

public boolean checkEdge(int src, int dst) {
if(matrix[src][dst] == 1) {
return true;
}
else {
return false;
}
}

public void print() {
System.out.print(" ");
for(Node node : nodes) {
System.out.print(node.data + " ");
}
System.out.println();

for(int i = 0; i < matrix.length; i++) {
System.out.print(nodes.get(i).data + " ");
for(int j = 0; j < matrix[i].length; j++) {
System.out.print(matrix[i][j] + " ");
}
System.out.println();
}
}
}
public class Node {
char data;

Node(char data){
this.data = data;
}
}

[@sriramarajuchintalapati1304]

why "nodes = new ArrayList();" , why not "nodes = new ArrayList();" in the Graph constructor?

[@joyceasante8292]

public class Main
{
public static void main(String[] args) {

Graph graph = new Graph(5);
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(2,3);
graph.addEdge(2,4);
graph.addEdge(4,0);
graph.addEdge(4,2);
graph.print();
System.out.println(graph.checkEdge(4,1));
}
}
******************************************
import java.util.*;
public class Graph{
ArrayList nodes;
int[][] matrix;
Graph(int size){
nodes = new ArrayList();
matrix = new int[size][size];
}
public void addNode(Node node){
nodes.add(node);
}
public void addEdge(int src, int dst){
matrix[src][dst] = 1;
}
public boolean checkEdge(int src, int dst){
if(matrix[src][dst] == 1){
return true;
}
else{
return false;
}
}
public void print(){
System.out.print(" ");
for(Node node : nodes){
System.out.print(node.data + " ");
}
System.out.println();


for(int i = 0; i < matrix.length; i++){
System.out.print(nodes.get(i).data + " ");

for(int j = 0; j < matrix[i].length;j++){
System.out.print(matrix[i][j] + " ");
}
System.out.println();
}
}
}
********************************
public class Node{
char data;
Node(char data){
this.data = data;
}
}

[@duy6930]

@@sriramarajuchintalapati1304 In Java, the syntax nodes = new ArrayList(); is a shorthand introduced in Java 7, known as the diamond operator. It allows you to omit the generic type on the right-hand side of the assignment when the compiler can infer it from the left-hand side.

[@fredericoamigo]

Once again, an other masterpiece from our favorite bro. Keep up the excellent work bro!

[@soicooc3500]

thanks i learn alot about you front html css js full cource and now i learn dsa , thank again

[@shinakuma6986]

why
public boolean checkEdge(int src, int dst) {
if(matrix[src][dst] == 1) {
return true;
}
else {
return false;
}
}
you could change the
int[ ][ ] matrix;
line into
boolean[ ][ ] matrix;
in the graph data structure and the checkEdge( ) function into
public boolean checkEdge(boolean src, boolean dst) {
return matrix[src][dst];
}
which would be a lot easier and the data structure would take a lot less space like instead of n^2 * sizeof(int) which is 4*n^2 bytes to n^2 * sizeof(boolean) which is 1 * n^2, other than that, a good video

[@cardsfanlv9371]

or if keeping the 0s and 1s are preferred could use byte data type.
public boolean checkEdge(int src, int dest) {
return matrix[src][dest] == 1;
}

[@yunanistan2364]

really really perfect approach 👍👍👍

[@wikkichris]

bro youre carrying my comp sci exam in school thank you man

[@Snowmanver2]

The video is extremely helpful, thank you Bro!

[@cardsfanlv9371]

The missing piece to this is - determining the index of the node. How would we know 'A' is node 0, 'B' is node 1, etc without some sort of lookup. Would probably store these in a hash map or table.

[@cardsfanlv9371]

in current setup you could do something like
int getIndexForNode(Node n) {
return nodes.indexOf(n);
}

[@georgekon69]

Booleans are better because they take less memory

[@ReviewGame10]

I had to do an assigment and this video saved me tyvm!!!!!

[@elionayzuridasilveira4140]

Thanks for this tutorial.👏

[@yunanistan2364]

very nice video thanks

[@nik1andr22]

Would it be better to use a boolean matrix instead of an int one?

[@silverseltzer2739]

Booleans in Java are printed as true or false. A boolean matrix would display “true” or “false” instead of the zeros and ones we want in our adjacency matrix.

[@emreotu4464]

Really nice!

[@berryallen5556]

God bless you bro!

[@Md.FirozeHossain]

Can you make two video series for Spring Boot(3.2+) and Angular (15+)

[@one111won]

wonderful stuff

[@CrazyD4RKiller1]

Great video bro

[@victorrezende6002]

Nice class

[@Memes_uploader]

Thank you for the video

[@tarekghosn3648]

here's a variable in java. 2 vids later. build a matrix why not... while your at it!

[@mmm6231]

Great!!

[@alaeeddinehajji]

Sit back, relax and enjoy the show

[@nailcutter8920]

why 1 is only between A and B, and not between B and A?

[@anthonymartinez71604]

Because the first is the source while the second is the destination. The edge only goes from A to B, not B to A

[@nailcutter8920]

@@anthonymartinez71604 thx!

[@wWvwvV]

I stopped here 3:34.

[@berryallen5556]

God bess you bro

[@TheNicoya77]

Great video. It would have been nice to add how to check if there is a cycle.

[@bulentoral1177]

Love you Bro

[@musicsadboizz]

nice man

[@MrLoser-ks2xn]

Thanks!

[@eugenezuev7349]

consumable