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Recursive algorithms in depth - Geek gap webinar #2
- 1. Tech Jobs InterviewsPreparation GeekGap Webinar #2 Presented by Junior Teudjio @junteudjio 02nd November 2019
- 2. Schedule Algorithms & DataStructures - What is an recursion? - How to solve a recursive problem? - Case study 1: Factorial - Case study 2: Recursive power - Case study 3: Recursive sum - Case study 4: Recursive reverse - Case study 5: Binary search - Case study 6: Fibonacci - Extra: Closing remarks on recursion
- 3. Algorithms & DataStructures What is recursion? A method of solving a problem where the solution depends on solutions to smaller instances of the same problem ~wikipedia Problem: Find the disk usage of a path.
- 4. Algorithms & DataStructures How to solve a recursive problem? 1. Solve the smallest/easiest instance of the problem 2. - Break the original problem into subproblems - Assume you had magical function to solve them 3. Combine the subproblems’ solutions to get the solution Problem: Find the disk usage of a path.
- 5. Algorithms & DataStructures How to solve a recursive problem? CODING TIME Problem: Find the disk usage of a path.
- 6. Algorithms & DataStructures How to solve a recursive problem? SOLUTION Problem: Find the disk usage of a path.
- 7. Algorithms & DataStructures Topic: Recursive algorithms QUESTIONS TIME Coming next: Case Study 1 ‘It's not that I'm so smart, it's just that I stay with problems longer.’ Albert Einstein
- 8. Algorithms & DataStructures Case study 1: Factorial 1. Solve the smallest/easiest instance of the problem 2. - Break the original problem into subproblems - Assume you had magical function to solve them 3. Combine the subproblems’ solutions to get the solution Problem: Write a recursive function to compute the factorial of a number. Problem Understanding:
- 9. Algorithms & DataStructures Case study 1: Factorial Problem: Write a recursive function to compute the factorial of a number. CODING TIME
- 10. Algorithms & DataStructures Case study 1: Factorial Problem: Write a recursive function to compute the factorial of a number. SOLUTION
- 11. Algorithms & DataStructures Case study 1: Factorial Problem: Write a recursive function to compute the factorial of a number. MEMORY COMPLEXITY ANALYSISTIME COMPLEXITY ANALYSIS
- 12. ‘talent is good practiceis better passion is best’ Frank Lloyd Wright Algorithms & Data Structures Topic: Recursive algorithms QUESTIONS TIME Coming next: Case Study 2
- 13. Algorithms & DataStructures Case study 2: Recursive power 1. Solve the smallest/easiest instance of the problem 2. - Break the original problem into subproblems - Assume you had magical function to solve them 3. Combine the subproblems’ solutions to get the solution Problem: Write a recursive function to compute x to the power of n (with n>=0) Problem Understanding:
- 14. Algorithms & DataStructures Case study 2: Recursive power Problem: Write a recursive function to compute x to the power of n (with n>=0) CODING TIME
- 15. Algorithms & DataStructures Case study 2: Recursive power Problem: Write a recursive function to compute x to the power of n (with n>=0) SOLUTION
- 16. Algorithms & DataStructures Case study 2: Recursive power Problem: Write a recursive function to compute x to the power of n (with n>=0) MEMORY COMPLEXITY ANALYSISTIME COMPLEXITY ANALYSIS
- 17. Algorithms & DataStructures Case study 2: Recursive power Problem: Write a recursive function to compute x to the power of n (with n>=0) OPTIMIZED SOLUTION
- 18. ‘The best theoryis inspired by practice.’ Donald Knuth Algorithms & Data Structures Topic: Recursive algorithms QUESTIONS TIME Coming next: Case Study 3
- 19. Algorithms & DataStructures Case study 3: Recursive reverse 1. Solve the smallest/easiest instance of the problem 2. - Break the original problem into subproblems - Assume you had magical function to solve them 3. Combine the subproblems’ solutions to get the solution Problem: Write a recursive function to reverse a list (L) in-place Problem Understanding:
- 20. Algorithms & DataStructures Case study 3: Recursive reverse Problem: Write a recursive function to reverse a list (L) in-place CODING TIME
- 21. Algorithms & DataStructures Case study 3: Recursive reverse Problem: Write a recursive function to reverse a list (L) in-place SOLUTION
- 22. Algorithms & DataStructures Case study 3: Recursive reverse Problem: Write a recursive function to reverse a list (L) in-place MEMORY COMPLEXITY ANALYSISTIME COMPLEXITY ANALYSIS
- 23. Algorithms & DataStructures Topic: Recursive algorithms QUESTIONS TIME Coming next: Case Study 4 ‘stay hungry, stay foolish’ Steve Jobs
- 24. Algorithms & DataStructures Case study 4: binary search 1. Solve the smallest/easiest instance of the problem 2. - Break the original problem into subproblems - Assume you had magical function to solve them 3. Combine the subproblems’ solutions to get the solution Problem: Write a recursive function to search of k in A, return True if found, False otherwise Problem Understanding:
- 25. Algorithms & DataStructures Case study 4: binary search Problem: Write a recursive function to search of k in A, return True if found, False otherwise CODING TIME
- 26. Algorithms & DataStructures Case study 4: binary search Problem: Write a recursive function to search of k in A, return True if found, False otherwise VERY BAD SOLUTION
- 27. Algorithms & DataStructures Case study 4: binary search Problem: Write a recursive function to search of k in A, return True if found, False otherwise SOLUTION
- 28. Algorithms & DataStructures Case study 4: binary search Problem: Write a recursive function to search of k in A, return True if found, False otherwise MEMORY COMPLEXITY ANALYSISTIME COMPLEXITY ANALYSIS
- 29. Algorithms & DataStructures Topic: Recursive algorithms QUESTIONS TIME Coming next: Case Study 5 ‘It's not that I'm so smart, it's just that I stay with problems longer.’ Albert Einstein
- 30. Algorithms & DataStructures Case study 5: fibonacci 1. Solve the smallest/easiest instance of the problem 2. - Break the original problem into subproblems - Assume you had magical function to solve them 3. Combine the subproblems’ solutions to get the solution Problem: Write a recursive function to compute the fibonacci of a number n. Problem Understanding:
- 31. Algorithms & DataStructures Case study 5: fibonacci Problem: Write a recursive function to compute the fibonacci of a number n. CODING TIME
- 32. Algorithms & DataStructures Case study 5: fibonacci Problem: Write a recursive function to compute the fibonacci of a number n. SOLUTION
- 33. Algorithms & DataStructures Case study 5: fibonacci Problem: Write a recursive function to compute the fibonacci of a number n. MEMORY COMPLEXITY ANALYSISTIME COMPLEXITY ANALYSIS
- 34. Algorithms & DataStructures Topic: Recursive algorithms QUESTIONS TIME Coming next: Closing remarks on recursion ‘talent is good practice is better passion is best’ Frank Lloyd Wright
- 35. Algorithms & DataStructures Closing remarks on recursion Remark 1: Beware of RecursionError: maximum recursion depth exceeded
- 36. Algorithms & DataStructures Closing remarks on recursion Remark 2: Take advantage of tail recursion
- 37. Algorithms & DataStructures Closing remarks on recursion Remark 2: Take advantage of memoization
- 38. Algorithms & DataStructures Topic: Recursive algorithms QUESTIONS TIME ‘stay hungry, stay foolish’ Steve Jobs
- 39. End of GeekGapWEBINAR #2 All the resources (slides, video, code) will be published on the site: www.geekgap.io NEXT WEBINAR 16 November 2019 | 17:00 - 20:00 (GMT) Schedule: Part 1: Algorithms & Data Structures - Hash Tables - Intro to Dynamic programming Part 2: System Design - REST APIs - Case Study: Django Rest Framework - Caching - Case Study: Redis Thanks!