Adjacency List Representation in DSA Typescript - Build from Scratch

Adjacency List Representation

📖 Scenario: Imagine you are organizing a small social network where each person can be friends with others. You want to store who is friends with whom in a way that is easy to look up and update.

🎯 Goal: You will build an adjacency list representation of a graph using a TypeScript object. Each key will be a person's name, and the value will be a list of their friends' names.

📋 What You'll Learn

Create an adjacency list object with exact keys and values

Add a new person with an empty friends list

Add friends to a person's list

Print the adjacency list to show the connections

💡 Why This Matters

🌍 Real World

Adjacency lists are used to represent networks like social connections, road maps, or computer networks efficiently.

💼 Career

Understanding adjacency lists is important for roles in software development, data analysis, and network engineering where graph data structures are common.

1

Create the initial adjacency list

Create a variable called adjacencyList as an object with these exact entries: 'Alice': ['Bob', 'Charlie'], 'Bob': ['Alice'], 'Charlie': ['Alice']

DSA Typescript

// Your code here

Hint

Use a TypeScript object with string keys and array of strings as values.

2

Add a new person with no friends

Add a new key 'David' to adjacencyList with an empty array as value

DSA Typescript

const adjacencyList: { [key: string]: string[] } = {
  'Alice': ['Bob', 'Charlie'],
  'Bob': ['Alice'],
  'Charlie': ['Alice']
};
// Your code here

Hint

Use bracket notation to add a new key with an empty array.

3

Add friends to David's list

Add 'Alice' and 'Bob' to adjacencyList['David'] array using push method

DSA Typescript

const adjacencyList: { [key: string]: string[] } = {
  'Alice': ['Bob', 'Charlie'],
  'Bob': ['Alice'],
  'Charlie': ['Alice']
};
adjacencyList['David'] = [];
// Your code here

Hint

Use push method twice to add two friends.

4

Print the adjacency list

Print the adjacencyList variable using console.log

DSA Typescript

const adjacencyList: { [key: string]: string[] } = {
  'Alice': ['Bob', 'Charlie'],
  'Bob': ['Alice'],
  'Charlie': ['Alice']
};
adjacencyList['David'] = [];
adjacencyList['David'].push('Alice');
adjacencyList['David'].push('Bob');
// Your code here

Hint

Use console.log(adjacencyList) to print the whole object.