My Simple Guide to Start Competitive Programming (From Zero to Hero Step by Step)

Nasrullah Sheikh Noman — Fri, 19 Jun 2026 19:11:12 +0000

🚀 Introduction

Competitive Programming (CP) is a skill where you solve algorithmic problems within a limited time. It helps you improve problem-solving ability, logical thinking, and coding speed.

If you are a complete beginner, don’t worry. This guide will help you start CP step by step.

🪜 Step 1: Learn a Programming Language

First, choose one language:

C++ (Highly recommended for CP)
OR Java / Python

👉 Focus on basics:

Variables
loops
conditionals
Functions
Arrays & strings

🧠 Step 2: Learn Basic Data Structures

Start with:

Array
String
Stack & Queue
Basic STL (for C++ users)

🔍 Step 3: Solve Easy Problems First

Start from easy level problems:

Codeforces (A problems)
CodeChef (Beginner section)
AtCoder Beginner Contest

👉 Don’t jump to hard problems early.

🔥 Step 4: Learn Important Topics Slowly

After basics:

Sorting
Binary Search
Greedy
Prefix Sum
Recursion
Basic DP (Dynamic Programming)

🏁 Step 5: Practice Daily

Solve 1–3 problems daily
Participate in contests
Upsolve (very important!)

🧩 Step 6: Learn from Mistakes

If you can’t solve a problem:

Read editorials
Understand logic
Try again yourself

💡 Final Tips

Consistency is more important than speed
Don’t compare yourself with others
Focus on understanding, not memorizing

MongoDB Query Practice Guide with Real Job Portal Dataset

Nasrullah Sheikh Noman — Tue, 12 May 2026 05:32:04 +0000

Overview

Recently, I practiced MongoDB queries using a sample Job Portal database.

Instead of learning operators in isolation, I used a realistic Job Portal dataset to better understand how MongoDB queries work in real-world applications.

Dataset Structure

A sample jobs collection was created with fields such as:

title
company
location
salary
experience
skills
applicants
status
department

Example Document

{
  title: "\"Software Engineer\","
  company: "TechCorp Bangladesh",
  salary: 75000,
  skills: ["JavaScript", "Node.js", "MongoDB"]
}

Topics Covered

1. Comparison Operators

Used for filtering documents based on value comparison.

Operators covered:

$eq
$ne
$gt
$gte
$lt
$lte

Example:

db.jobs.find({
  salary: { $gt: 70000 }
})

2. Logical Operators

Combining multiple query conditions.

Operators covered:

$and
$or
$not
$nor

Example:

db.jobs.find({
  $or: [
    { location: "Dhaka" },
    { isRemote: true }
  ]
})

3. Array Query Operators

Working with array fields such as skills.

Operators covered:

$in
$nin
$all
$size
$elemMatch

Example:

db.jobs.find({
  skills: { $all: ["Python", "SQL"] }
})

4. Update Operators

Updating existing documents.

Operators covered:

$set
$inc
$push
$pull

Example:

db.jobs.updateOne(
  { title: "Frontend Developer" },
  { $push: { skills: "TypeScript" } }
)

5. Projection, Sorting & Pagination

Topics covered:

Field selection
Sorting
Limiting results
Pagination

Example:

db.jobs.find({}, { title: 1, salary: 1, _id: 0 })
  .sort({ salary: -1 })
  .limit(5)

6. Aggregation Pipeline

Used for analytics and reporting.

Operators covered:

$match
$group
$project
$sort

Example use case:

Calculate average salary by department.

7. Advanced Aggregation

Production-level query operations.

Operators covered:

$lookup
$unwind
$facet

Useful for:

Joining collections
Dashboard analytics
Multi-stage reporting

Key Learning

MongoDB becomes significantly easier to understand when practiced using realistic datasets instead of isolated examples.

Next Learning Goals

MongoDB Indexing
Mongoose ODM
MongoDB Atlas
Transactions

Thanks for reading.

mongodb #backend #nodejs #database #webdev

DEV Community: Nasrullah Sheikh Noman

My Simple Guide to Start Competitive Programming (From Zero to Hero Step by Step)

🚀 Introduction

🪜 Step 1: Learn a Programming Language

👉 Focus on basics:

🧠 Step 2: Learn Basic Data Structures

🔍 Step 3: Solve Easy Problems First

🔥 Step 4: Learn Important Topics Slowly

🏁 Step 5: Practice Daily

🧩 Step 6: Learn from Mistakes

💡 Final Tips

MongoDB Query Practice Guide with Real Job Portal Dataset

Overview

Dataset Structure

Example Document

Topics Covered

1. Comparison Operators

2. Logical Operators

3. Array Query Operators

4. Update Operators

5. Projection, Sorting & Pagination

6. Aggregation Pipeline

7. Advanced Aggregation

Key Learning

Next Learning Goals

mongodb #backend #nodejs #database #webdev