• Last Updated : 30 Jun, 2021

Examples:

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Input: adjList[] = {{0 –> 1 –> 3}, {1 –> 2}, {2 –> 3}}
Output:
0 1 0 1
0 0 1 0
0 0 0 1
0 0 0 0

Input: adjList[] = {{0 –> 1 –> 4}, {1 –> 0 –> 2 –> 3 –> 4}, {2 –> 1 –> 3}, {3 –> 1 –> 2 –> 4}, {4 –> 0 –> 1 –> 3}}
Output:
0 1 0 0 1
1 0 1 1 1
0 1 0 1 0
0 1 1 0 1
1 1 0 1 0

Adjacency List: An array of lists is used. The size of the array is equal to the number of vertices. Let the array be an array[]. An entry array[i] represents the list of vertices adjacent to the ith Vertex.

Adjacency Matrix: Adjacency Matrix is a 2D array of size V x V where V is the number of vertices in a graph. Let the 2D array be adj[][], a slot adj[i][j] = 1 indicates that there is an edge from vertex i to vertex j.

• Initialize a matrix with 0s.
• Iterate over the vertices in the adjacency list
• For every jth vertex in the adjacency list, traverse its edges.
• For each vertex i with which the jth vertex has an edge, set mat[i][j] = 1.

Below is the implementation of the above approach:

## C++

 `// C++ Program to implement``// the above approach``#include ``using` `namespace` `std;` `// Function to insert vertices to adjacency list``void` `insert(vector<``int``> adj[], ``int` `u, ``int` `v)``{``    ``// Insert a vertex v to vertex u``    ``adj[u].push_back(v);``    ``return``;``}` `// Function to display adjacency list``void` `printList(vector<``int``> adj[], ``int` `V)``{``    ``for` `(``int` `i = 0; i < V; i++) {``        ``cout << i;``        ``for` `(``auto` `j : adj[i])``            ``cout << ``" --> "` `<< j;``        ``cout << endl;``    ``}``    ``cout << endl;``}` `// Function to convert adjacency``// list to adjacency matrix``vector > convert(vector<``int``> adj[],``                             ``int` `V)``{``    ``// Initialize a matrix``    ``vector > matrix(V,``                                ``vector<``int``>(V, 0));` `    ``for` `(``int` `i = 0; i < V; i++) {``        ``for` `(``auto` `j : adj[i])``            ``matrix[i][j] = 1;``    ``}``    ``return` `matrix;``}` `// Function to display adjacency matrix``void` `printMatrix(vector > adj, ``int` `V)``{``    ``for` `(``int` `i = 0; i < V; i++) {``        ``for` `(``int` `j = 0; j < V; j++) {``            ``cout << adj[i][j] << ``"   "``;``        ``}``        ``cout << endl;``    ``}``    ``cout << endl;``}` `// Driver code``int` `main()``{``    ``int` `V = 5;` `    ``vector<``int``> adjList[V];` `    ``// Inserting edges``    ``insert(adjList, 0, 1);``    ``insert(adjList, 0, 4);``    ``insert(adjList, 1, 0);``    ``insert(adjList, 1, 2);``    ``insert(adjList, 1, 3);``    ``insert(adjList, 1, 4);``    ``insert(adjList, 2, 1);``    ``insert(adjList, 2, 3);``    ``insert(adjList, 3, 1);``    ``insert(adjList, 3, 2);``    ``insert(adjList, 3, 4);``    ``insert(adjList, 4, 0);``    ``insert(adjList, 4, 1);``    ``insert(adjList, 4, 3);` `    ``// Display adjacency list``    ``cout << ``"Adjacency List: \n"``;``    ``printList(adjList, V);` `    ``// Function call which returns``    ``// adjacency matrix after conversion``    ``vector > adjMatrix``        ``= convert(adjList, V);` `    ``// Display adjacency matrix``    ``cout << ``"Adjacency Matrix: \n"``;``    ``printMatrix(adjMatrix, V);` `    ``return` `0;``}`

## Java

 `// Java program to implement``// the above approach``import` `java.util.*;` `class` `GFG{` `// Function to insert vertices to adjacency list``static` `void` `insert(Vector adj[],``                   ``int` `u, ``int` `v)``{``    ` `    ``// Insert a vertex v to vertex u``    ``adj[u].add(v);``    ``return``;``}` `// Function to display adjacency list``static` `void` `printList(Vector adj[],``                      ``int` `V)``{``    ``for``(``int` `i = ``0``; i < V; i++)``    ``{``        ``System.out.print(i);` `        ``for``(``int` `j : adj[i])``            ``System.out.print(``" --> "` `+ j);``            ` `        ``System.out.println();``    ``}``    ``System.out.println();``}` `// Function to convert adjacency``// list to adjacency matrix``static` `int``[][] convert(Vector adj[],``                       ``int` `V)``{``    ` `    ``// Initialize a matrix``    ``int` `[][]matrix = ``new` `int``[V][V];` `    ``for``(``int` `i = ``0``; i < V; i++)``    ``{``        ``for``(``int` `j : adj[i])``            ``matrix[i][j] = ``1``;``    ``}``    ``return` `matrix;``}` `// Function to display adjacency matrix``static` `void` `printMatrix(``int``[][] adj, ``int` `V)``{``    ``for``(``int` `i = ``0``; i < V; i++)``    ``{``        ``for``(``int` `j = ``0``; j < V; j++)``        ``{``            ``System.out.print(adj[i][j] + ``" "``);``        ``}``        ``System.out.println();``    ``}``    ``System.out.println();``}` `// Driver code``public` `static` `void` `main(String[] args)``{``    ``int` `V = ``5``;` `    ``@SuppressWarnings``(``"unchecked"``)``    ``Vector []adjList = ``new` `Vector[V];``    ``for``(``int` `i = ``0``; i < adjList.length; i++)``        ``adjList[i] = ``new` `Vector();``        ` `    ``// Inserting edges``    ``insert(adjList, ``0``, ``1``);``    ``insert(adjList, ``0``, ``4``);``    ``insert(adjList, ``1``, ``0``);``    ``insert(adjList, ``1``, ``2``);``    ``insert(adjList, ``1``, ``3``);``    ``insert(adjList, ``1``, ``4``);``    ``insert(adjList, ``2``, ``1``);``    ``insert(adjList, ``2``, ``3``);``    ``insert(adjList, ``3``, ``1``);``    ``insert(adjList, ``3``, ``2``);``    ``insert(adjList, ``3``, ``4``);``    ``insert(adjList, ``4``, ``0``);``    ``insert(adjList, ``4``, ``1``);``    ``insert(adjList, ``4``, ``3``);` `    ``// Display adjacency list``    ``System.out.print(``"Adjacency List: \n"``);``    ``printList(adjList, V);` `    ``// Function call which returns``    ``// adjacency matrix after conversion``    ``int``[][] adjMatrix = convert(adjList, V);` `    ``// Display adjacency matrix``    ``System.out.print(``"Adjacency Matrix: \n"``);``    ``printMatrix(adjMatrix, V);``}``}` `// This code is contributed by amal kumar choubey`

## Python3

 `# Python3 program to implement``# the above approach`` ` `# Function to insert vertices``# to adjacency list``def` `insert(adj, u, v):` `    ``# Insert a vertex v to vertex u``    ``adj[u].append(v)``    ``return` `# Function to display adjacency list``def` `printList(adj, V):``    ` `    ``for` `i ``in` `range``(V):``        ``print``(i, end ``=` `'')``        ` `        ``for` `j ``in` `adj[i]:``            ``print``(``' --> '` `+` `str``(j), end ``=` `'')``            ` `        ``print``()``        ` `    ``print``()``        ` `# Function to convert adjacency``# list to adjacency matrix``def` `convert(adj, V):` `    ``# Initialize a matrix``    ``matrix ``=` `[[``0` `for` `j ``in` `range``(V)]``                 ``for` `i ``in` `range``(V)]``    ` `    ``for` `i ``in` `range``(V):``        ``for` `j ``in` `adj[i]:``            ``matrix[i][j] ``=` `1``    ` `    ``return` `matrix`` ` `# Function to display adjacency matrix``def` `printMatrix(adj, V):``    ` `    ``for` `i ``in` `range``(V):``        ``for` `j ``in` `range``(V):``            ``print``(adj[i][j], end ``=` `' '``)``            ` `        ``print``()``        ` `    ``print``()``        ` `# Driver code``if` `__name__``=``=``'__main__'``:` `    ``V ``=` `5`` ` `    ``adjList ``=` `[[] ``for` `i ``in` `range``(V)]`` ` `    ``# Inserting edges``    ``insert(adjList, ``0``, ``1``)``    ``insert(adjList, ``0``, ``4``)``    ``insert(adjList, ``1``, ``0``)``    ``insert(adjList, ``1``, ``2``)``    ``insert(adjList, ``1``, ``3``)``    ``insert(adjList, ``1``, ``4``)``    ``insert(adjList, ``2``, ``1``)``    ``insert(adjList, ``2``, ``3``)``    ``insert(adjList, ``3``, ``1``)``    ``insert(adjList, ``3``, ``2``)``    ``insert(adjList, ``3``, ``4``)``    ``insert(adjList, ``4``, ``0``)``    ``insert(adjList, ``4``, ``1``)``    ``insert(adjList, ``4``, ``3``)`` ` `    ``# Display adjacency list``    ``print``(``"Adjacency List: "``)``    ``printList(adjList, V)`` ` `    ``# Function call which returns``    ``# adjacency matrix after conversion``    ``adjMatrix ``=` `convert(adjList, V)`` ` `    ``# Display adjacency matrix``    ``print``(``"Adjacency Matrix: "``)``    ``printMatrix(adjMatrix, V)`` ` `# This code is contributed by rutvik_56`

## C#

 `// C# program to implement``// the above approach``using` `System;``using` `System.Collections.Generic;` `class` `GFG{` `// Function to insert vertices to adjacency list``static` `void` `insert(List<``int``> []adj,``                        ``int` `u, ``int` `v)``{``    ` `    ``// Insert a vertex v to vertex u``    ``adj[u].Add(v);``    ``return``;``}` `// Function to display adjacency list``static` `void` `printList(List<``int``> []adj,``                           ``int` `V)``{``    ``for``(``int` `i = 0; i < V; i++)``    ``{``        ``Console.Write(i);` `        ``foreach``(``int` `j ``in` `adj[i])``            ``Console.Write(``" --> "` `+ j);``            ` `        ``Console.WriteLine();``    ``}``    ``Console.WriteLine();``}` `// Function to convert adjacency``// list to adjacency matrix``static` `int``[,] convert(List<``int``> []adj,``                           ``int` `V)``{``    ` `    ``// Initialize a matrix``    ``int` `[,]matrix = ``new` `int``[V, V];` `    ``for``(``int` `i = 0; i < V; i++)``    ``{``        ``foreach``(``int` `j ``in` `adj[i])``            ``matrix[i, j] = 1;``    ``}``    ``return` `matrix;``}` `// Function to display adjacency matrix``static` `void` `printMatrix(``int``[,] adj, ``int` `V)``{``    ``for``(``int` `i = 0; i < V; i++)``    ``{``        ``for``(``int` `j = 0; j < V; j++)``        ``{``            ``Console.Write(adj[i, j] + ``" "``);``        ``}``        ``Console.WriteLine();``    ``}``    ``Console.WriteLine();``}` `// Driver code``public` `static` `void` `Main(String[] args)``{``    ``int` `V = 5;` `    ``List<``int``> []adjList = ``new` `List<``int``>[V];``    ``for``(``int` `i = 0; i < adjList.Length; i++)``        ``adjList[i] = ``new` `List<``int``>();``        ` `    ``// Inserting edges``    ``insert(adjList, 0, 1);``    ``insert(adjList, 0, 4);``    ``insert(adjList, 1, 0);``    ``insert(adjList, 1, 2);``    ``insert(adjList, 1, 3);``    ``insert(adjList, 1, 4);``    ``insert(adjList, 2, 1);``    ``insert(adjList, 2, 3);``    ``insert(adjList, 3, 1);``    ``insert(adjList, 3, 2);``    ``insert(adjList, 3, 4);``    ``insert(adjList, 4, 0);``    ``insert(adjList, 4, 1);``    ``insert(adjList, 4, 3);` `    ``// Display adjacency list``    ``Console.Write(``"Adjacency List: \n"``);``    ``printList(adjList, V);` `    ``// Function call which returns``    ``// adjacency matrix after conversion``    ``int``[,] adjMatrix = convert(adjList, V);` `    ``// Display adjacency matrix``    ``Console.Write(``"Adjacency Matrix: \n"``);``    ``printMatrix(adjMatrix, V);``}``}` `// This code is contributed by amal kumar choubey`

## Javascript

 ``
Output:
```Adjacency List:
0 --> 1 --> 4
1 --> 0 --> 2 --> 3 --> 4
2 --> 1 --> 3
3 --> 1 --> 2 --> 4
4 --> 0 --> 1 --> 3

0   1   0   0   1
1   0   1   1   1
0   1   0   1   0
0   1   1   0   1
1   1   0   1   0```

Time Complexity: O(N*M)
Auxiliary Space: O(N2)

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