My Journey to solve more than 200 leetcode question in 3 months:

I have followed Striver's sde sheet because the way he explains the algorithms is exceptional.

Link here >>> https://takeuforward.org/strivers-a2z-dsa-course/strivers-a2z-dsa-course-sheet-2/

Intro:

I am a software engineer with more than 5 years of technical experience in Angular/React/Java/C#, having worked with great teams and learned many things while working on projects.

Bio:

I am an Front End Developer developer and I love working on front end technologies because it is easy to execute any business logic due to its fewer complexities.

Front-end framework like Angular are mostly used when the project deals with many APIs (product API, cart API, order API, profile API, etc.), while React, on the other hand, focuses primarily on rapid front-end development by incorporating JavaScript code, adding some routes, including SSR, and you are done with MVP. I am not talking about Redux as it is mandatory afterward when your components need state management at later stages of development.

Angular, on the other hand, requires a bit more learning, and believe me, my colleagues are shifting from React to Angular because they think Angular is cooler than React.

Turning into a Java Developer: 

Public string BecomeAJavaDeveloper(boolean canDoDsa){
  if(canDoDsa){
       "You should never quit;Keep solving more dsa question to have hands on the algorithms";
  }else{
       "Dont worry! Free and Paid lectures are there in internet to help you. I recommend CodeWithHarry for java basics and then straight away attempt to solve ds and algo questions referring any sheet (from leetcode,codestudio,gfg) so that you will be able to analyse the algorithm once you see any question";
  }

}        

My Quick Journey

At first, I learned the basic things like how to write variables and data types, string and array methods, reading and printing data, ArrayList, HashMap, HashSet, PriorityQueue, Deque, Stacks, Queues. (Source: YouTube (apnaCollege ,CodeWithHarry))(Day 0 - 4-5 hours)

Easy/Medium (Source: Leetcode, CodeStudio and GeekForGeeks)

1.Solve strings and arrays question- (Greedy, Heap, Sliding Window,Stacks and queues) questions -> here you will learn PriorityQueue,Queues and Stacks, Two pointers,Sliding window,Kadane's Algorithm,Boyer Moore Voting algorithm etc.

Arrays and Strings(Greedy, Heap, Sliding Window,Stacks and queues):

Day1:

• Fizz buzz https://leetcode.com/problems/fizz-buzz/
• Matrix diagonal sum https://leetcode.com/problems/matrix-diagonal-sum/ Concatenation of array https://leetcode.com/problems/concatenation-of-array/ Maximum number of words found in sentences https://leetcode.com/problems/maximum-number-of-words-found-in-sentences/description/ ? ?
• Maximum of absolute value expression https://leetcode.com/problems/maximum-of-absolute-value-expression/ Spiral matrix ii https://leetcode.com/problems/spiral-matrix-ii/description/ Maximum gap https://leetcode.com/problems/maximum-gap/
• Maximum subarray https://leetcode.com/problems/maximum-subarray/
• Set matrix zeroes https://leetcode.com/problems/set-matrix-zeroes/description/

Day 2:

• Next permutation https://leetcode.com/problems/next-permutation/
• Longest subarray non negative integers https://www.geeksforgeeks.org/problems/length-of-longest-subarray0440/1?itm_source=geeksforgeeks&itm_medium=article&itm_campaign=bottom_sticky_on_article ? ?
• Richest customer wealth https://leetcode.com/problems/richest-customer-wealth/description/
• Running sum of 1d array https://leetcode.com/problems/running-sum-of-1d-array/description/
• Special positions in a binary matrix(Hashmap solution pending) https://leetcode.com/problems/special-positions-in-a-binary-matrix/description/

Day 3:

• Convert 1d array into 2d array https://leetcode.com/problems/convert-1d-array-into-2d-array/description/ ? ?
• Search a 2d matrix ii https://leetcode.com/problems/search-a-2d-matrix-ii/description/
• Range sum query 2d immutable https://leetcode.com/problems/range-sum-query-2d-immutable/description/
• Max chunks to make sorted https://leetcode.com/problems/max-chunks-to-make-sorted/description/
• Sum of all submatrices of a given matrix https://www.geeksforgeeks.org/sum-of-all-submatrices-of-a-given-matrix/ ? ? ? ?

Day 4:

• Max chunks to make sorted ii https://leetcode.com/problems/max-chunks-to-make-sorted-ii/description/
• Transpose matrix https://leetcode.com/problems/transpose-matrix/description/
• Count negative numbers in a sorted matrix https://leetcode.com/problems/count-negative-numbers-in-a-sorted-matrix/description/
• Reshape the matrix https://leetcode.com/problems/reshape-the-matrix/description/
• Matrix diagonal sum https://leetcode.com/problems/matrix-diagonal-sum/
• Minimum swaps required to bring all elements less than or equal to k together https://www.geeksforgeeks.org/problems/minimum-swaps-required-to-bring-all-elements-less-than-or-equal-to-k-together4847/1?itm_source=geeksforgeeks&itm_medium=article&itm_campaign=bottom_sticky_on_article

Day 5

• Rearrange array in alternating positive & negative items with O(1)? https://leetcode.com/problems/rearrange-array-elements-by-sign/description/ ? ?
• Find greatest common divisor of array https://leetcode.com/problems/find-greatest-common-divisor-of-array/
• Self dividing numbers https://leetcode.com/problems/self-dividing-numbers/ Number of good pairs https://leetcode.com/problems/number-of-good-pairs/ Subtract the Product and Sum of Digits of an Integer https://leetcode.com/problems/subtract-the-product-and-sum-of-digits-of-an-integer/
• Count of Matches in Tournament https://leetcode.com/problems/count-of-matches-in-tournament/submissions/
• Max consecutive ones https://leetcode.com/problems/max-consecutive-ones/ Largest number divides x co prime y https://www.geeksforgeeks.org/largest-number-divides-x-co-prime-y/

Day 6:

• Implement rand10 using rand7 https://leetcode.com/problems/implement-rand10-using-rand7/description/
• Four divisors https://leetcode.com/problems/four-divisors/description/
• Total number divisors given number https://www.geeksforgeeks.org/total-number-divisors-given-number/
• Number Of Open Doors https://www.geeksforgeeks.org/problems/number-of-open-doors1552/1
• Day of the week https://leetcode.com/problems/day-of-the-week/

Day 7:

• Finding Position https://www.geeksforgeeks.org/problems/finding-position2223/1
• Rectangle overlap https://leetcode.com/problems/rectangle-overlap/description/
• Excel sheet column title https://leetcode.com/problems/excel-sheet-column-title/ ? ?
• Unique paths https://leetcode.com/problems/unique-paths/
• Rectangle area https://leetcode.com/problems/rectangle-area/description/
• Check if array pairs are divisible by k https://leetcode.com/problems/check-if-array-pairs-are-divisible-by-k/

Day 8:

• Subsequences of size three in an array whose sum is divisible by m https://www.geeksforgeeks.org/subsequences-size-three-array-whose-sum-divisible-m/
• Factorial trailing zeroes https://leetcode.com/problems/factorial-trailing-zeroes/
• Permutation sequence https://leetcode.com/problems/permutation-sequence/description/
• Nth magical number https://leetcode.com/problems/nth-magical-number/description/
• Find nth magic number https://www.geeksforgeeks.org/find-nth-magic-number/

Day 9

• Max Consecutive Ones
• Max Consecutive Ones III
• Subarrays with K Different Integers
• Merge Intervals
• Jump Game

Day 10

• Jump Game II
• Largest Rectangle in Histogram
• Assign Cookies
• Fractional Knapsack
• N meetings in one room

Day 11

• Minimum Platforms
• Job Sequencing Problem
• Insert Interval
• Kth Largest Element in an Array
• Merge K Sorted Arrays

Day 12

• Task Scheduler
• Hand of Straights
• Design Twitter
• Kth Largest Element in a Stream
• Maximum Sum Combinations
• Find Median from Data Stream
• Top K Frequent Elements

Strings:(Includes Two Pointer,Heaps and Greedy Questions)

Day 13

• Valid Parentheses
• Generate Parentheses
• ?Sort Characters By Frequency
• Minimum Insertions to Balance a Parentheses String
• Minimum Window Substring

Day 14

• Minimum Window Subsequence
• Number of Substrings Containing All Three Characters
• Longest Substring with At Most K Distinct Characters
• Count With K Different Characters
• Maximum Nesting Depth of the Parentheses

Day 15

• Reverse Words in a String
• Longest Palindromic Substring
• Sum of Beauty of All Substrings
• Valid Anagram
• Rotate String
• Sort Characters By Frequency

Solve Binary Search problems - Implement lower bound, upper bound, and related problems, Koko eating bananas, aggressive cows, painter's partition, etc.

Day 16

• Implement Lower Bound
• Implement Upper Bound
• Search Insert Position
• Ceil The Floor
• Find First and Last Position of Element in Sorted Array
• Count occurences of a number in a sorted array with duplicates

Day 17

• Search in Rotated Sorted Array
• Search in Rotated Sorted Array II
• Find Minimum in Rotated Sorted Array
• Find out how many times the array has been rotated
• Single Element in a Sorted Array

Day 18

• Find Peak Element
• Koko Eating Bananas
• Minimum days to make M bouquets
• ?Find the Smallest Divisor Given a Threshold
• Capacity To Ship Packages Within D Days

Day 19

• Kth Missing Positive Number
• Book Allocation Problem
• Split Array Largest Sum
• Painter's Partition Problem
• Minimize Max Distance to Gas Station

Day 20

• Median of Two Sorted Arrays
• Kth element of two sorted Arrays
• Find the row with maximum number of 1's
• Search in a 2D Matrix
• Search in a row and column wise sorted matrix
• Find a Peak Element II

Solve Recursion and Backtracking problems

Day 21

• Generate Parentheses
• Print All Subsequences
• Combination Sum
• Combination Sum II
• Subsets II
• Combination Sum III

Day 22

• Palindrome Partitioning
• N-Queens
• Word Search
• Rat in a maze
• Word Break
• Sudoku Solver

Solve LinkedLists Problems

Day 23(Linked List)

• Insert Node At The Beginning
• Delete Node in a Linked List
• Count Nodes of a Linked List
• Search in a Linked List

Day 24

• Middle of the Linked List
• ?Reverse Linked List(Iterative and recursive)
• Linked List Cycle
• Linked List Cycle II
• Palindrome Linked List
• Odd Even Linked List
• Remove Nth Node From End of List
• Delete the Middle Node of a Linked List

Day 25

• Sort List
• Intersection of Two Linked Lists
• Add Two Numbers
• Rotate List
• Flatten A Linked List

Day 26 (DLL)

• ?Insert at end of Doubly Linked List
• ?Delete Last Node of a Doubly Linked List
• Reverse A Doubly Linked List
• Delete all occurrences of a given key in a doubly linked list
• Find pairs with given sum in doubly linked list
• Remove duplicates from a sorted Doubly Linked List?

Solve Binary Trees and Binary Search Trees Questions

Day 27

• Create Binary Tree
• Tree Traversals
• Binary Tree Preorder Traversal
• Binary Tree Inorder Traversal
• Binary Tree Postorder Traversal
• Binary Tree Level Order Traversal

Day 28

• Maximum Depth of Binary Tree
• Balanced Binary Tree
• Binary Tree Maximum Path Sum
• Same Tree
• Binary Tree Zigzag Level Order Traversal
• Boundary of Binary Tree
• Binary Tree Right Side View
• Symmetric Tree

Day 29

• All Root to Leaf Paths In Binary Tree.
• Lowest Common Ancestor of a Binary Tree
• Maximum Width of Binary Tree
• Children Sum Property
• All Nodes Distance K in Binary Tree

Day 30

• Time To Burn Tree
• Count Complete Tree Nodes
• Construct Binary Tree from Preorder and Inorder Traversal
• Construct Binary Tree from Inorder and Postorder Traversal
• Serialize and Deserialize Binary Tree
• Binary Tree Inorder Traversal

Day 31(Binary Search Tree)

• Search in a Binary Search Tree
• Minimum element in BST
• Ceil from BST
• Floor from BST
• Insert into a Binary Search Tree

Day 32

• Insert into a Binary Search Tree
• Delete Node in a BST
• Kth Smallest Element in a BST
• Validate Binary Search Tree
• Lowest Common Ancestor of a Binary Search Tree

Day 33

• Construct Binary Search Tree from Preorder Traversal
• Inorder Successor in BST
• Binary Search Tree Iterator
• Two Sum IV - Input is a BST
• Size of Largest BST in Binary Tree

Solve Graph Problems Covering BFS/DFS,Topo Sort,Shortest Path Algorithms

Day 34(Graphs)

• Number of Connected Components in an Undirected Graph
• BFS in Graph
• DFS Traversal
• Number of Provinces
• Rotting Oranges

Day 35

• Flood Fill
• Detect Cycle in an Undirected Graph
• Matrix BFS Problem
• Surrounded Regions
• Number of Enclaves

Day 36

• Word Ladder
• ?Word Ladder II
• Number of Distinct Islands II
• Is Graph Bipartite?
• Course Schedule II

Day 37

• Using Kahn's Algo Topological Sort
• Detect Cycle In A Directed Graph
• Course Schedule
• Course Schedule 2
• Find Eventual Safe States
• Alien Dictionary

Day 38

• Shortest Path in UG with Unit weights
• Shortest Path in DAG
• Dijkstra's shortest path
• ?Shortest Path in Binary Matrix
• Path With Minimum Effort

Day 39

• Cheapest Flights Within K Stops
• Network Delay Time
• Number of Ways to Arrive at Destination
• ?Bellman Ford
• Floyd Warshall

Day 40

• Minimum Spanning Tree
• Data Stream As Disjoint Intervals
• Kruskal’s Minimum Spanning Tree Algorithm
• Number of Operations to Make Network Connected
• Most Stones Removed with Same Row or Column

Day 41

• Accounts Merge
• No of Islands
• ?Making A Large Island
• Swim in Rising Water
• Critical Connections in a Network
• Articulation point
• Count Strongly Connected Components (Kosaraju’s Algorithm)

Solve Dynamic programming problems: Don't forget to go through the steps from Brute force (recursion) to memoization to DP and at last space optimisation.Specially for dp you can watch LoveBabbar and striver videos. I started DP right after recursion, you can do after LinkedList, BT and BST and graph first.Its your choice

Day 42 1D DP

• ?Climbing Stairs
• Frog Jump
• Frog Jump with k distance
• ?House Robber
• House Robber II

Day 43 2D/3D DP

• Ninja’s Training
• Unique Paths
• Unique Paths II
• Minimum Path Sum
• Minimum Path Sum in a Triangular Grid
• Minimum Falling Path Sum
• Chocolate Pickup

Day 44 (Dp on Subsequences)

• Subset Sum Equal To K
• Partition Equal Subset Sum
• ?Partition Array Into Two Arrays to Minimize Sum Difference
• Count Subsets with Sum K
• Partitions with Given Difference

Day 45

• Knapsack Problem
• Minimum Coins
• Target Sum
• Coin Change II
• Unbounded Knapsack
• Rod cutting problem

Day 46 (DP on strings)

• Longest Common Subsequence
• Print longest common subsequence
• Longest Common Substring
• Longest Palindromic Subsequence
• Minimum Insertion Steps to Make a String Palindrome

Day 47

• Delete Operation for Two Strings
• Shortest Common Supersequence?
• Distinct Subsequences
• ?Edit Distance
• Wildcard Matching

Day 48 (DP On stocks)

• Best Time to Buy and Sell Stock
• Best Time to Buy and Sell Stock II
• Best Time to Buy and Sell Stock III
• Best Time to Buy and Sell Stock IV
• Best Time to Buy and Sell Stock with Cooldown
• Best Time to Buy and Sell Stock with Transaction Fee

Day 49 (DP on LIS)

• Longest Increasing Subsequence
• Largest Divisible Subset
• Longest String Chain
• Longest Bitonic Sequence
• Number of Longest Increasing Subsequence

Day 50 MCM DP

• Matrix Chain Multiplication
• Minimum Cost to Cut a Stick
• Burst Balloons
• Parsing A Boolean Expression
• Palindrome Partitioning II
• Partition array for maximum sum

Remaining 10 DAYS:Solve Unknown Problems, Revision,Attend Mock Interviews

When you have time you can practice few Math problems and Bit Manupulation problem

It's never late to start learning DS and algo. Just take your time and find the best course structure that suits to your needs.