Note: Questions you might (not) get the answers to, but you will gain enough clarity get those answers yourself.

• Is competitive programming necessary? How to balance college, programming and other aspects?
• Does language matter? What language to start with? How to approach learning a new language?
• Is development really necessary or we can directly start with competitive programming? What should be my first preference (development or competitive programming)?

Event Flow

Side note: Shoutout to tsecgeeks.in for documenting Dive into Code, my first talk around this topic.

Educating oneself about the difference

• Polls
  • What are we here to do today?
  • How many of you have solved at least on CP/DSA problem?
  • How many of you have built at least one project using any language?
• Disclaimer
  • !(speaker to audience session)
  • A conversation between peers. Feel to answer others’ question if you want to.
  • About asking questions.
• What is DSA?
  • Data structures: A Data Structure is a way to organize data to allow processing of a large amount of data in a relatively short period of time.
  • Algorithm: Algorithms are well-defined sets of instructions designed that are used to solve problems or perform a task.
  • What does a DSA problem look like?
    • You are given a set of instructions.
    • You have to figure out to solve the problem using a specific Data Structure and Algorithm.
• What is competitive programming?
  • Poll: What platforms do you know?
  • CP is a mind sport just like any other sport.
  • There are variables like time, speed and accuracy involved.
• DSA vs CP
  • What to do and thinking what to do
  • Quick vs Efficient
  • code quality
  • LL, BST are never used in CP
  • Answer to this is very goal specific actually but I try to put my opinion.
  • CP: It helps you build a problem solving mindset, improves code reading ability, debugging faster, optimising. (which is essentially what some companies are looking for in interviews.)
• Why competitive programming?
  • with developing Problem Solving skills.
  • to be a quick thinker.
  • to think about efficency in terms of time and memory limits.
  • And also, it is a part of recruitment/shortlisting for some companies for full time job roles.
• How do I start?
  • Level 1: Learn a language > Learn Standard lib(inbuilt) > Hackerrank
  • Level 2: Solve problems
  • Level 3: Participate in contests > Practice > Upsolve
• Anatomy of a CP Problem
  • Title
  • Problem Statement
  • Input/Output format
  • Constraints
  • Memory and Time Limits
  • Sample Test Cases
  • Explanation
• Sample Problem
  • Navigating through Codeforces and Hackerrank

Strategies

• Solving strategy
  • Reading the problem and understanding the problem.
  • Filter the noise and make observations as you read.
  • Connect the dots and do something which you do know
  • Constraints.
  • Don’t jump to the code. Think first.
  • Counter intutiveness about the think twice, code once.
  • Don’t always optimize. If nothing works, try Brute Force.
  • Edge Cases.
  • Eg: Write a program to add 2 numbers.
• Contest strategy
  • Don’t look at the leaderboard.
  • Probably look at the number of submissions.
  • Move to the next problem if you have given sufficient time to a problem.
    • Come back at it with a fresh perspective.
• Upsolving strategy
  • What is Upsolving?
  • Do n + 1 th problem from a contest.
  • Read others’ code.
    • Clean code?
    • Better implementation?
      • Eg: Reversing a bit.
• Editorial reading strategy
  • Don’t jump to the climax.
    • Don’t look at the code directly.
    • Go step by step, line by line.
    • Try it after each line.
    • Even if you look at the code, do not copy paste.
      • Write the code yourself.
    • Let it go if it doesn’t make sense today.
      • Don’t take things too personally. It might make sense tomorrow.

Mistakes I made

• Not getting out of my comfort zone.
• Moving to look at others’ solutions quickly.
• Not being consistent.
• Giving up.

Generalizations

• If we take a broader look, and zoom out a little from this scenario — it emulates real time problem solving.
  • Reading the problem and understanding it.
  • Understanding the requirements.
  • Thinking about an approach. (Design)
  • Thinking about efficency. (Feasability)
  • Coding out the problem. (Development)
  • Result of the problem. (Speed, Time, Testing)

Real Time Examples

• Harsh Kapadia’s Git Graph
• React’s Diffing Algorithm
• React’s Source code: Internal packages

Some prestigious contests

• Codechef Snackdown
• ICPC (Internation Collegiate Programming Contest)
  • Team competition which happens annually across the world, that consists of several rounds.
  • Team of 3
  • Regionals (3-4 in india)
  • Asia finals
  • World finals
• Google Kickstart, Hashcode and CodeJam
• Facebook Hacker Cup
• Codechef Snackdown

How much time to spend on solving a problem?

From where to practice?

Platforms:

• Hackerrank
• Codeforces
• Codechef
• AtCoder’s
• Leetcode

For beginners:

• AtCoder’s, ABC every Saturday 5 PM IST
• Codechef, STARTER every Wednesday 8 PM IST
• Codeforces, Div 3

How to start practicing?

• Implementation, constructive algo, Ad Hoc and greedy

How to stay consistent

• Start enjoying the work, if you tell yourself consciously after sometime subconsciously you will start enjoying it.
• Make a peer group if 2-3 people who have same goal.
  • Hold each other accountable, and keep each others motivated.
• Have short discussions after contest.
• If practice gets boring then start learning any new DS/Algo.
• Have a growth mindset, and take responsibility for yourself.