Original resource By (https://github.com/ZeeshanAdilButt/Data-Structures-RoadMap/blob/main/README.md)

Some considerations while starting with problem-solving till 100+ Leetcode problems are solved:

• Start with the most-easiest problems.
• DO NOT try to solve each problem yourself, instead try to learn and understand how different problems are being solved
• Do not try to solve a problem for more than 1 hour initially to get fast and to achieve more in less time, for any problem taking more than 1 hour, put it in a backlog and solve it later
• The average time to solve a problem should be 30-45 minutes
• Do not try to solve a lot of problems from one topic, instead try to solve 5-10 problems per topic
• Do not try to jump into problem-solving directly without the necessary pre-requisites, For example
• If you are trying to solve a problem that requires HashSet/HashMap then make sure you have studied HashMap before solving the problem If you are trying to solve a problem that uses recursion, first make sure you learn recursion properly If you are trying to solve a problem that uses graphs/trees, first make sure you learn graphs/tree properly If you are trying to solve a problem that uses dynamic programming, first make sure you learn dynamic programming properly.

• Basic Understanding of Data structures in your language (C++ STL, C# Collections, Python Standard Library)

• If you like C++ and more details > My code school Data Structures

https://www.youtube.com/playlist?list=PL2_aWCzGMAwI3W_JlcBbtYTwiQSsOTa6P (C++)

• If you like Python > code basics - Data Structures

https://www.youtube.com/playlist?list=PLeo1K3hjS3uu_n_a__MI_KktGTLYopZ12

• Introduction to Hash Tables and Dictionaries by CS Dojo:

https://www.youtube.com/watch?v=sfWyugl4JWA

• Easy String Algorithms

1. String as character arrays:

video: https://www.youtube.com/watch?v=TkTgo_7ab0M&pp=ygUQcHJpbnQgY2hhcmFjdGVycw%3D%3D

2. Count characters in string

video: https://www.youtube.com/watch?v=kWr0TIjO6nU

3. Arrays & Hashing:_

• Contains Duplicate

video: https://www.youtube.com/watch?v=3OamzN90kPg problem: https://leetcode.com/problems/contains-duplicate/

• Valid Anagram:

video: https://www.youtube.com/watch?v=9UtInBqnCgA problem: https://leetcode.com/problems/valid-anagram

• Two Sum:

video: https://www.youtube.com/watch?v=KLlXCFG5TnA problem: (https://leetcode.com/problems/two-sum/)

• Length of Last word:

video: https://www.youtube.com/watch?v=KT9rltZTybQ&list=PLot-Xpze53lfQmTEztbgdp8ALEoydvnRQ&index=27 problem:

• Search Insert Position

video: https://www.youtube.com/watch?v=K-RYzDZkzCI&list=PLot-Xpze53lfQmTEztbgdp8ALEoydvnRQ&index=23 problem:

4. Two Pointers:_

V- alid Palindrome

video: https://leetcode.com/problems/valid-palindrome/ problem: https://leetcode.com/problems/valid-palindrome/

• Best time to buy and Sell Stock:

video: https://www.youtube.com/watch?v=1pkOgXD63yU&list=PLot-Xpze53lfQmTEztbgdp8ALEoydvnRQ&index=7&pp=iAQB problem: https://leetcode.com/problems/best-time-to-buy-and-sell-stock/

S- tack & Queue Problems:_

6. alid Parenthesis

video: https://www.youtube.com/watch?v=WTzjTskDFMg problem: https://leetcode.com/problems/valid-parentheses/

Implement Stack using Queue:

video: https://www.youtube.com/watch?v=rW4vm0-DLYc&list=PLot-Xpze53lfxD6l5pAGvCD4nPvWKU8Qo&index=10 problem: https://leetcode.com/problems/implement-stack-using-queues/

Implement Queue using Stack:

video: https://www.youtube.com/watch?v=3Et9MrMc02A&pp=ygUabmVldGNvZGUgcXVldWUgdXNpbmcgc3RhY2s%3D problem: https://leetcode.com/problems/implement-queue-using-stacks/

Sqrt(x)

problem: https://leetcode.com/problems/sqrtx/ video:

704 Binary Search

problem: https://leetcode.com/problems/binary-search/ video:

Count Negative Numbers in a Sorted Matrix

problem: https://leetcode.com/problems/count-negative-numbers-in-a-sorted-matrix/ video:

Peak Index in a Mountain Array

problem: https://leetcode.com/problems/peak-index-in-a-mountain-array/ video: Find Peak element:

video: https://www.youtube.com/watch?v=CFgUQUL7j_c problem: Maximum Sub Array:

video: https://www.youtube.com/watch?v=5WZl3MMT0Eg&list=PLot-Xpze53lfQmTEztbgdp8ALEoydvnRQ&index=4 problem: https://leetcode.com/problems/maximum-subarray/ Recursion Course ( don't watch the trees or graphs section): https://www.youtube.com/watch?v=IJDJ0kBx2LM

Linked List Course:_

course with problems (find all the similar problems on leetcode): video: https://www.youtube.com/watch?v=Hj_rA0dhr2I&pp=ygUXbGlua2VkbGlzdCBmcmVlY29kZWNhbXA%3D

Linked list problems:_

Reverse Linked List

https://leetcode.com/problems/reverse-linked-list/ https://www.youtube.com/watch?v=G0_I-ZF0S38

Merge 2 sorted Lits

https://leetcode.com/problems/merge-two-sorted-lists/ https://www.youtube.com/watch?v=XIdigk956u0

Linked List Cycle

https://leetcode.com/problems/linked-list-cycle/ https://www.youtube.com/watch?v=gBTe7lFR3vc

Reverse Linked List - Iterative AND Recursive

video: https://www.youtube.com/watch?v=G0_I-ZF0S38&list=PLot-Xpze53lfQmTEztbgdp8ALEoydvnRQ&index=10&pp=iAQB code: https://leetcode.com/problems/reverse-linked-list/

Palindrome Linked List

video: https://www.youtube.com/watch?v=yOzXms1J6Nk&list=PLot-Xpze53lfQmTEztbgdp8ALEoydvnRQ&index=13 problem:

Remove Linked List element:

video: https://www.youtube.com/watch?v=JI71sxtHTng&list=PLot-Xpze53lfQmTEztbgdp8ALEoydvnRQ&index=21&pp=iAQB problem:

Hash table 1- Happy Number https://leetcode.com/problems/happy-number/

2- Isomorphic Strings https://leetcode.com/problems/isomorphic-strings/

3- Missing Number https://leetcode.com/problems/missing-number/

4- Word Pattern https://leetcode.com/problems/word-pattern/

5- Next Greater Element I https://leetcode.com/problems/next-greater-element-i/

Trees Recursion Course (watch the trees section): https://www.youtube.com/watch?v=IJDJ0kBx2LM

Trees Full Course: https://www.youtube.com/watch?v=fAAZixBzIAI

Graphs Recursion Course ( watch the graphs section): https://www.youtube.com/watch?v=IJDJ0kBx2LM

Graphs Full Course:

https://www.youtube.com/watch?v=tWVWeAqZ0WU

1-Find the Town Judge

video: https://www.youtube.com/watch?v=ZUP_tIs4VaE

problem https://leetcode.com/problems/find-the-town-judge/

2- Find Center of Star Graph

video: https://www.youtube.com/watch?v=KEKcW6eLyEY

problem: https://leetcode.com/problems/find-center-of-star-graph/

3-Find if Path Exists in Graph

video: https://www.youtube.com/watch?v=QC4bDHEnmLM&pp=ygUfMTc5MS4gRmluZCBDZW50ZXIgb2YgU3RhciBHcmFwaA%3D%3D

problem: https://leetcode.com/problems/find-if-path-exists-in-graph/

DFS 1- Binary Tree Inorder Traversal

video: https://youtu.be/g_S5WuasWUE problem: https://leetcode.com/problems/binary-tree-inorder-traversal 2- Binary Tree Preorder Traversal

video: https://youtu.be/afTpieEZXck problem: https://leetcode.com/problems/binary-tree-preorder-traversal 3- Binary Tree Postorder Traversal

video: https://youtu.be/QhszUQhGGlA problem: https://leetcode.com/problems/binary-tree-postorder-traversal 4- Validate Binary Search Tree

video: https://youtu.be/s6ATEkipzow problem: https://leetcode.com/problems/validate-binary-search-tree 5- Path Sum

video: https://youtu.be/LSKQyOz_P8I problem: https://leetcode.com/problems/path-sum 6- Pacific Atlantic Water Flow

video: https://youtu.be/s-VkcjHqkGI problem: https://leetcode.com/problems/pacific-atlantic-water-flow BFS 1- Binary Tree Level Order Traversal

video: https://youtu.be/6ZnyEApgFYg problem: https://leetcode.com/problems/binary-tree-level-order-traversal 2- Maximum Depth of Binary Tree

video: https://youtu.be/hTM3phVI6YQ problem: https://leetcode.com/tag/breadth-first-search/ 3- Same Tree

video: https://youtu.be/vRbbcKXCxOw problem: https://leetcode.com/problems/same-tree/ Graph Algorithm for Technical Interview video: https://youtu.be/tWVWeAqZ0WU

Dynamic Programming (DP): Dynamic Programming (DP) Full Course: https://www.youtube.com/watch?v=oBt53YbR9Kk&t=29s

Easy Problems:

Counting Bits: https://leetcode.com/problems/counting-bits/ Video: https://youtu.be/AgMr5uojxbM

Divisor Game: https://leetcode.com/problems/divisor-game/ Video: https://www.youtube.com/watch?v=UbE4-ONpJcc&ab_channel=Fraz

Climbing Stairs: https://leetcode.com/problems/climbing-stairs/ Video: https://youtu.be/UUaMrNOvSqg

Best Time to Buy and Sell Stock: https://leetcode.com/problems/best-time-to-buy-and-sell-stock/ Video: https://youtu.be/excAOvwF_Wk

Min Cost Climbing Stairs: https://leetcode.com/problems/min-cost-climbing-stairs/ Video: https://youtu.be/8TDeGdY6qaM

Fibonacci Number: https://leetcode.com/problems/fibonacci-number/ Video: https://youtu.be/WvffCsh3Nt4

N-th Tribonacci Number: https://leetcode.com/problems/n-th-tribonacci-number/ Video: https://youtu.be/WvffCsh3Nt4

Medium Problems:

Word Break: https://leetcode.com/problems/word-break/ Video: https://youtu.be/_iIK7Gu7MNo

House Robber: https://leetcode.com/problems/house-robber/ Video: https://youtu.be/ZwDDLAeeBM0

Maximum Subarray: https://leetcode.com/problems/maximum-subarray/ Video: https://youtu.be/6HntYGZyjZI

simple trick backtracking is DP which undoes its operation if it doesn't find the answer: 1- Letter Combinations of a Phone Number problem https://leetcode.com/problems/letter-combinations-of-a-phone-number/ video: https://www.youtube.com/watch?v=irkG33phXuw

2- The k-th Lexicographical String of All Happy Strings of Length n problem https://leetcode.com/problems/the-k-th-lexicographical-string-of-all-happy-strings-of-length-n/ video: https://www.youtube.com/watch?v=t3Hb0NYOA1c

++++++++++++++++++++++++++++++++++++++++++ Some more nice problems (to be updated): Best Time to Buy and Sell Stock

First Bad Version

Isomorphic Strings

Two Sum

Squares of a Sorted Array

Merge Two Sorted Lists

Is Subsequence

Two Sum II - Input Array Is Sorted

Rotate Array

Reverse Linked List

Search Insert Position

Some good resources (to be updated): Bit Manipulation Reading: https://www.youtube.com/watch?v=7jkIUgLC29I

• Love Babbar: Follow Love Babbar's YouTube channel for insightful explanations and problem-solving techniques.
• Fraz: Explore Fraz's YouTube content for in-depth discussions on programming and algorithms.

• LeetCode: Sharpen your coding skills and tackle algorithmic challenges.
• GeeksforGeeks: Access a wide range of data structures and algorithms problems with detailed explanations.
• Code Ninja: Engage in coding challenges and competitions to enhance your problem-solving skills.

• C++ Programming from Problem Analysis to Program Design: This book is an excellent resource for mastering C++ concepts, problem analysis, and program design.

• Codeforces: Participate in competitive programming contests and improve your algorithmic skills.
• HackerRank: Solve coding challenges and enhance your proficiency in various domains.

1. C++ Basics: Variables, loops, conditionals, functions, and basic syntax.
2. Arrays: Manipulation, searching, and sorting algorithms.
3. Linked Lists: Singly linked lists, doubly linked lists, and circular linked lists.
4. Stacks and Queues: Implementation and real-world applications.
5. Trees: Binary trees, binary search trees, and tree traversal algorithms.
6. Graphs: Representation, traversal, and common algorithms (DFS, BFS).
7. Sorting Algorithms: Bubble sort, selection sort, merge sort, quicksort.
8. Searching Algorithms: Binary search, linear search.
9. Dynamic Programming: Solving optimization problems using dynamic programming.
10. Hashing: Hash functions, collision resolution, and applications.
11. Greedy Algorithms: Problem-solving using the greedy approach.
12. Bit Manipulation: Operations, counting set bits, and bitwise XOR.
13. Recursion: Understanding and implementing recursive solutions.

Feel free to combine insights from these resources for a well-rounded learning experience. If you're contributing to this repository, consider sharing your solutions or insights gained from these resources to benefit the community.