Top 10 Data Structures Topics Every Programmer Should Master

Why Data Structures Matter

Data structures determine how efficiently a program runs. Choosing the right data structure can reduce execution time and memory usage. Interviewers often focus on data structures to evaluate problem-solving skills and logical thinking.

1. Array

Arrays store elements in contiguous memory locations. They provide fast access using indexes and are widely used in almost every application.

let numbers = [10, 20, 30, 40]
console.log(numbers[2])

2. String

Strings store sequences of characters. Many interview problems involve string manipulation such as reversing, searching, or pattern matching.

function reverseString(str) {
  return str.split("").reverse().join("")
}

reverseString("programming")

3. Linked List

A linked list stores data in nodes, where each node points to the next node. It allows efficient insertion and deletion compared to arrays.

class Node {
  constructor(value) {
    this.value = value
    this.next = null
  }
}

4. Stack

Stacks follow the Last In First Out principle. They are used in function calls, undo operations, and expression evaluation.

class Stack {
  constructor() {
    this.items = []
  }

  push(value) {
    this.items.push(value)
  }

  pop() {
    return this.items.pop()
  }
}

5. Queue

Queues follow the First In First Out principle. They are commonly used in scheduling, buffering, and task processing.

class Queue {
  constructor() {
    this.items = []
  }

  enqueue(value) {
    this.items.push(value)
  }

  dequeue() {
    return this.items.shift()
  }
}

6. Hash Table

Hash tables store key-value pairs and provide fast lookup, insertion, and deletion. They are used in caching and indexing.

let user = {
  name: "Amit",
  age: 28
}

console.log(user.name)

7. Set

A set stores unique values and automatically removes duplicates. It is useful when uniqueness is required.

let uniqueNumbers = new Set([1, 2, 3, 3, 4])
console.log(uniqueNumbers)

8. Tree

Trees represent hierarchical data. They are used in file systems, databases, and UI components.

function traverse(node) {
  if (node === null) return
  traverse(node.left)
  traverse(node.right)
}

9. Graph

Graphs represent networks of connected nodes. They are used in social networks, maps, and recommendation systems.

function dfs(node, visited = new Set()) {
  if (visited.has(node)) return
  visited.add(node)

  for (let neighbor of node.neighbors) {
    dfs(neighbor, visited)
  }
}

10. Heap

Heaps are specialized trees used to efficiently find minimum or maximum values. They are used in priority queues and scheduling algorithms.

class MinHeap {
  constructor() {
    this.heap = []
  }
}

Common Mistakes

Many programmers struggle with data structures due to common mistakes.

• Choosing the wrong data structure
• Ignoring time complexity
• Not understanding basic operations
• Memorizing instead of understanding

Best Practices

Mastering data structures requires practice and consistency.

• Understand use cases for each structure
• Practice coding problems regularly
• Analyze time and space complexity
• Write clean and readable code