AswinBarath/SDE-Sheet

SDE Sheet problem solving on data structures and algorithms

SDE Sheet

SDE Sheet is a list for Mastering Problem Solving with Data Structures and Algorithms in 30 Days

Calendar progress

January 2022

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-	-	-	-	-	-	1 ❌
2 ❌	3 ❌	4 ❌	5 ❌	6 ❌	7 ❌	8 ❌
9 ✅	10 ✅	11 ❌	12 ❌	13 ❌	14 ❌	15 ❌
16 ✅	17 ❌	18 ❌	19 ✅	20 ❌	21 ❌	22 ❌
23 ❌	24 ❌	25 ❌	26 ❌	27 ❌	28 ✅	29 ❌
30 ❌	31 ❌	-	-	-	-	-

February 2022

Su	Mo	Tu	We	Th	Fr	Sa
-	-	1 ❌	2 ❌	3 ❌	4 ❌	5 ❌
6 ❌	7 ❌	8 ❌	9 ❌	10 ❌	11 ❌	12 ❌
13 ✅	14	15	16	17	18	19
20	21	22	23	24	25	26
27	28	-	-	-	-	-

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🔴 Striver's SDE Sheet

• Myth: You should be really good at competitive programming
• Reality:
  • Solving a bunch of 150-200 questions from GFG or Leetcode can get you stronger at Data Structures and Algorithms
  • Solving 150-200 questions gets your problem solving skills up
  • Because you are covering every Algorithm, you are covering Data Structure, you are covering every topic that could be possibly asked in the interview
  • So, once you are done with this 150 - 200 questions, what happens is, you are really good at your problem-solving skills or you are really good at your data structures and algorithms skills
  • And apparently, you are able to crack those interviews
  • This 150 - 200 questions helps you crack the majority of the product based companies in India
• Striver's SDE Sheet: takeuforward.org/interviews/strivers-sde-sheet-top-coding-interview-problems/
• This 180 questions will take you 1 month (30 days) if you are already into programming.
• For every day, you need to around 8 to 10 hours, a proper 8 to 10 hours.
• You should be able to spend 8 to 10 hours because you are wanting to get into India's top most companies and for that you have to sacrifice 8 to 10 hours per day for around 30 to 60 days (1 - 2 months).
• If you cannot do this, then product based companies do not deserve you, there might be someone else who is waiting for you.
• So, if you spend 8 - 10 hours per day to solve 6 questions for 30 days without having any cheat days in between, You would have solved 180 questions at the end of the 30 days.
• After that 30 days, you should be really good at DSA and you should be able to crack any of the product based companies' interviews.
• You have the list, how will you solve the problems:
  • Let's say, you are solving the problem find the middle of Linked list
  • Search for "middle of Linked list leetcode" on google
  • Open the leetcode problem link, try to solve the problem
  • Now, for best solution go to the Discuss Section and search for Most Votes
  • Sometimes you can go to Solution section of Leetcode
  • If you are not satisfied with those places for solutions, search "middle of Linked list gfg" on google
  • Go to the GFG article and refer the best solutions
• Source of questions:
  • Striver's interview Experience,
  • Leetcode premium (lists),
  • Striver's work experience at GFG

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Note taking Tips from Striver

• Take a notepad, whenever you are solving a problem and you have successfully solved the problem on Leetcode or GFG, do this:
  • Write a function snippet in your notepad
  • So, what eventually happens is that after 180 questions, all these questions function snippets will be in your notepad
  • Now, make sure that every morning you should revise it (Apply Active Recall study technique)
• Doing this on the first day may take you 4 hours,
  • the next day it might take you 3 hours,
  • and the next day it will surely take you 2 hours,
  • on the next day it will take you 1 hour and
  • eventually a day will come where it will hardly take 10 - 15 minutes.
  • You will be just crawling thourgh the pages and you will totally get it
  • and everything will stay in your mind
• Don't memorize it, instead:
  • remember the approaches for the solving the problems,
  • remember the best complextity
• So, if you remember the approaches, you have your implementation skills, you can easily implement in the interview
• So, you should keep revising in the notepad on a daily basis
• Keep doing this till you are interviewing with companies

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Interview Prep Requirements

• Striver's Core Sheet: takeuforward.org/interviews/must-do-questions-for-dbms-cn-os-interviews-sde-core-sheet/
• Core Subjects: DBMS, Computer Networks, Operating Systems
• Prepare notes from Striver's Core Sheet Website above
• Resume:
  • Make sure to write those things in resume which you can answer if the interviewer asks you
• Projects:
  • You should be ready with a reason for each project you created
  • Which tech stack you have used, and say why you preferred this tech stack and what other tech stacks did you consider
  • What are the difficulties you faced in your projects and what did you do to overcome them
  • So, create a script of 4 - 5 pages on above points for your projects
  • The interviewer will judge on briefing skills, how are you representing the project
• Problem solving rounds:
  • If you know the given problem, do not jump into the solution directly:
    • because this will make the interviewer change the question
    • and it throws a negative impression that you do not know how to represent yourself in the interview
  • So, intially start off with the Brute-force approach:
    • Say the brute-force approach to the interviewer
    • Run some test cases on your brute-force approach
    • Say the time complexity and space complexity
    • Two things may happen:
      • The interviewer may ask you to code the brute-force
      • Or might ask you to make the brute-force approach better
  • Now, spend 5 to 10 minutes to present your thought process to getting towards the optimal appraoch
    • Write some test cases
    • Do some dry run
  • Now, you give the efficient approach to the interviewer. Once he is satisfied, provide the time complexity and space complexity
  • Now, the interviewer will ask you to code it:
    • Do not blindly write the code, that's a common mistake
    • Ask the interviewer that "Should I only write the function?" or "Should I write the entire code?"
    • Most of the cases, the interviewer will say "Yes" to write function snippet
    • Now, you write the code snippet in such a way that you are in the ears of the interviewer every time:
      • When you write the function, you tell him this function will do this and this
      • If you take two parameters, tell him that the 1st parameter is this and 2nd parameter is this, intially I will pass this and this
      • Tell him you are intiializing this and this
      • Do this until he/she says "please write the code and then once you are done then you can explain"
  • This process of interviewing send them the message that you actually want the job and you are really prepared and you are really motivated to bag it

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Note taking - Ground rules

• Topicwise, note down what type of problem uses which pattern to be solved via which type of optimization

Topicwise: Problem - Pattern - Optimization

• Problem Solving Goal on Day-to-Day basis:

3 hours / day         =  6 Questions per day
6 Q's / day     * 30  =  180 Questions per month
180 Q's / month * 4   =  720 Questions in 4 months

• Problem Solving is more important than note making, so don't stress too much in notes/documentation

Why SDE Sheet?

• Solving 150 - 200 DS ALGO Questions on leetcode gets your problem solving skills up 💹

SDE Sheet Problems

✅/❌	No.	Problem	Pattern(s)	Opimization
Arrays
✅	1	Sort an array of 0’s 1’s 2’s without using extra space or sorting algo
✅	2	Repeat and Missing Number
✅	3	Merge two sorted Arrays without extra space
✅	4	Kadanes Algorithm
✅	5	Merge Overlapping Subintervals
✅	6	Find the duplicate in an array of N+1 integers
✅	7	Set Matrix Zeroes
✅	8	Pascal's Triangle
✅	9	Next Permutation
✅	10	Count Inversions in an array
✅	11	Best Time to Buy and Sell Stock
✅	12	Rotate Image
✅	13	Search a 2D Matrix
✅	14	Pow(x, n)
✅	15	Majority Element
✅	16	Majority Element II
✅	17	Unique Paths
✅	18	Reverse Pairs
Hashmaps
✅	19	Two Sum
✅	20	4Sum
✅	21	Longest Consecutive Sequence
✅	22	Largest subarray with 0 sum
✅	23	Count the number of subarrays having a given XOR
❌	24	Longest Substring Without Repeating Characters
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