This Repository Contains Various Approaches to Solving a Problem, Serves as a Guide to Preparing for Interviews
- Number of Elementary Operations that can be done in 1 Sec is 10^8. If your algorithm is achieving it in <=10^8 (Including Constraints), then we can use bruteforce approach to solve the problem.
Use the information in a question to your advantage! It will often implicitly tell you how efficient your algorithm should be to get full points. Consider the fact that a computer can run 108 iterations per second. You’re usually going to be given an array or string; call its size n. Note that you cannot be asked to come up with a solution better than O(n) in this case (even if one exists); the reason is that it takes linear time to input the test array itself! With that in mind,
- If (n >= 10^4), aim for a O(n) or a O(n log n) solution.
- If (n <= 10^3), aim for a O(n2) solution
- I(n <= 10^2), aim for a O(n3) solution
- If (n < 20), a O(2n) solution should be fine.
- Detailed Complexity for each constraint can be found here : https://www.geeksforgeeks.org/overcome-time-limit-exceedtle/
- https://discuss.codechef.com/t/no-of-operations-computations-in-1-second-java/13889
| Operation | ArrayList | LinkedList | HashSet | HashMap | TreeMap |
|---|---|---|---|---|---|
| Access (get) | O(1) | O(n) | N/A | N/A | O(log n) |
| Search (contains) | O(n) | O(n) | O(1) | O(1) | O(log n) |
| Insert (add at end) | O(1) | O(1) | O(1) | O(1) | O(log n) |
| Insert (add at specific index) | O(n) | O(n) | N/A | N/A | O(log n) |
| Delete (remove at end) | O(1) | O(1) | O(1) | O(1) | O(log n) |
| Delete (remove at specific index) | O(n) | O(n) | N/A | N/A | O(log n) |
| Sort (using default comparator) | O(n log n) | O(n log n) | N/A | N/A | O(n log n) |
| Sort (using custom comparator) | O(n log n) | O(n log n) | N/A | N/A | O(n log n) |
| Count Occurrences | O(n) | O(n) | O(n) | O(n) | O(n) |
| Synchronized View | O(1) | O(1) | O(1) | O(1) | O(1) |
| Unmodifiable View | O(1) | O(1) | O(1) | O(1) | O(1) |
Note:
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ArrayList and LinkedList are different implementations of the List interface.
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HashSet, HashMap, and TreeMap are implementations of the Set and Map interfaces.
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N/A indicates that the operation is not applicable for that particular data structure.
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Synchronized View: Functions like Collections.synchronizedList(), Collections.synchronizedSet(), and Collections.synchronizedMap() return synchronized (thread-safe) views of the specified collections.
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Unmodifiable View: Functions like Collections.unmodifiableList(), Collections.unmodifiableSet(), and Collections.unmodifiableMap() return unmodifiable views of the specified collections, making them read-only.
- DSA Concepts & Program Implemnetation Visually : https://opendsa-server.cs.vt.edu/ODSA/Books/Everything/html/index.html
- Neetcode - https://www.youtube.com/@NeetCode/playlists
- Striver's DSA Sheet : https://takeuforward.org/strivers-a2z-dsa-course/strivers-a2z-dsa-course-sheet-2/
- GFG SDE Sheet : https://geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/
- https://github.com/TheAlgorithms
- https://www.enjoyalgorithms.com/
- https://github.com/ashishps1/awesome-leetcode-resources
- Algorithms : https://www.algorithm-archive.org/
- https://www.techinterviewhandbook.org/
- https://github.com/jwasham/coding-interview-university
- Problems : https://www.techiedelight.com/
- https://github.com/ashishps1/awesome-leetcode-resources
- https://cp-algorithms.com/
- Best Theory Explanations
- Abdul Bari
- Best Visual Explanations
- https://www.designgurus.io/blind75
- https://www.techinterviewhandbook.org/grind75
- https://neetcode.io/practice
- https://algo.monster/dashboard
- https://cses.fi/problemset/ (https://github.com/Jonathan-Uy/CSES-Solutions)
- https://www.interviewcake.com/
- Leetcode Problems Company Wise : https://leetracer.com/screener
- Java Core Concepts in Detail : https://jenkov.com/
- https://www.geeksforgeeks.org/java/
- Datastructures in Java : https://youtu.be/WqDvLBOaWXY
- Collections in Java : https://www.youtube.com/playlist?list=PLFGoYjJG_fqoDQHufg7XVk-yb2w6CNpgF
- Java Code Visulizer : https://pythontutor.com/java.html
- Algorithms Visualization
- Height Map Visualizer : https://editor.p5js.org/LeweyM/full/RpAxMlZL4