Algorithm design and analysis
- 1. RECURSION AND BACKTRAKING (Memoization, D&C, Combinations) Present On 1. Hemalkumar Buha Guide By :- Prof Sayara Banu
- 2. TOPIC Backtracking Introduction Examples Of Backtracking Advantages Disadvantages No Solution Yes Solution
- 3. INTRODUCTION History o ‘Backtrack’ the word was first introduced by Dr. D.H. Lehmer in 1950s. o R.J. Walker was the first man who gave algorithmic description in 1960. o Later developed by S. Golamb and L. Baumert.
- 4. BACKTRACKING o Definition Constraint satisfaction. Modified process of BFA(brute force approach). o Types of problems in backtracking 1. Decision 2. Enumeration 3. Optimization
- 5. BACKTRACKING ALGORITHM Explore 1. if N is a goal node, return “Success”. 2. If N is a leaf node ,return “failure”. 3. For each child (C) of N, 3.1 Explore C 3.1.1. if C was successful, return “Success”. 4. Return “failure”.
- 6. EXAMPLE 1) N-Queens 2) Gold Tunnel 3) Puzzles 4) Maze 5) Knight
- 7. EXPLAIN WITH N-QUEENS • 4x4 Chase board arrange 4 queens that no two queens attack each other. • Queens attack on horizontally, vertically or diagonally. • So we will start by placing the first queen. Q Q Q Q
- 10. GOLD TUNNEL PROBLEM • 3 Tunnel (Progress) 1 2 3 Gold Bag Root
- 11. ADVANTAGES 1. Simple to implement. 2. More effective than dynamic programming. 3. Easy to code. 4. Code size is usually small.
- 12. DISADVANTAGES 1. Multiple functions calls are expensive. 2. Inefficient when there is lots of branching from one state. 3. Requires large amount of space as the each function state needs to be stored on system stack.
- 13. REFERENCES • www.udemy.com • www.hackerearth.com • www.geeksforgeeks.org • www.slideshare.net
- 14. CERTIFICATE