JAVA - SCRIPT-ADJACENCY MATRIX CODE

JAVA PYTHON GO KOTLIN C# RUBY C++ Java Script

Example :

<html>
<body>    
<script>

    function insertEdge(i, j) {
        adjacentMatrix[i][j] = true
    }	

    function removeEdge(i, j) {
        adjacentMatrix[i][j] = false
    }

    function printAdjacencyMatrix() {
        for (let i = 0; i < adjacentMatrix.length; i++) {
            for (let j = 0; j < adjacentMatrix[i].length; j++) {
                var val = adjacentMatrix[i][j] ? 1 : 0
                document.write("| ",val," | ")
            }	
            document.write("</br>")
        }
    }		

    const V = 5

    var adjacentMatrix = Array.from({ length: V }, () => 
                                        Array.from({ length: V }, () => false)
                          );

    //Insert Edges

    insertEdge(0, 1)
    insertEdge(0, 2)
    insertEdge(0, 3)

    insertEdge(1, 0)
    insertEdge(1 ,4)

    insertEdge(2, 0)
    insertEdge(2, 3)
    insertEdge(2, 4)

    insertEdge(3, 0)
    insertEdge(3 ,2)
    insertEdge(3, 4)

    insertEdge(4, 3)
    insertEdge(4, 2)
    insertEdge(4, 1)

    document.write("+---------------------+</br>")
    printAdjacencyMatrix()
    document.write("+---------------------+</br>")

</script>
</body>
</html>

Output :

    

   +---------------------------+
   | 0 | | 1 | | 1 | | 1 | | 0 | 
   | 1 | | 0 | | 0 | | 0 | | 1 | 
   | 1 | | 0 | | 0 | | 1 | | 1 | 
   | 1 | | 0 | | 1 | | 0 | | 1 | 
   | 0 | | 1 | | 1 | | 1 | | 0 | 
   +---------------------------+

Code explanation for Adjacency Matrix Data Structure

The code for Adjacency Matrix is quite simple.

There are two important methods defined above :

function insertEdge(i, j)

function removeEdge(i, j)

As the name of the method suggests insertEdge(...), is used to add an Edge to the Adjacency Matrix.

Explanation of function insertEdge(i, j) method :

function insertEdge(i, j) {
	adjacentMatrix[i][j] = true
}

So, the actual adjacency matrix, we are going to create, looks like the below structure,

Now, if we look at the min program. We create a 2D array, that holds either true or false.

const V = 5
var adjacentMatrix = Array.from({ length: V }, () =>
									Array.from({ length: V }, () => false)
					);

So, the above line creates a 2D array with 5 rows and 5 columns that initially contains false.

Now, all we need to do is, wherever we want to insert an edge. We will mark it with value true.

Say, for example :

There is an edge in [0][1] (As mentioned in the adjacency matrix above).

All we are doing is, calling the function insertEdge(...) method,

insertEdge(0, 1)

and passing 0 and 1 as parameters.

And in the function insertEdge(...) method, we have the below line,

adjacentMatrix[i][j] = true

Now, since value of i = 0 and j = 1,

adjacentMatrix[0][1] = true

And adjacentMatrix[0][1] is marked to true.

In other words, we have inserted an edge in adjacentMatrix[0][1] above.

Similarly, we insert the edges one by one, calling the function insertEdge(...) method.

insertEdge(0, 2)
insertEdge(0, 3)
...
...
...

Explanation of function removeEdge(i, j) method :

Even, to delete an Edge, we follow the same steps.

As we know, there is an Edge in [0][2]. To remove it, all we need to do is call,

removeEdge(0, 2)

And mark that particular location to false.

function removeEdge(i, j) {
	adjacentMatrix[i][j] = false
}

And the Edge is deleted.

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