complete search Flashcards
What is Complete Search, and how does it work?
Complete Search, also known as recursive backtracking or brute force, is a method for solving a problem by exhaustively searching the entire search space to obtain a solution. It involves exploring all possible solutions and using recursive backtracking to avoid unnecessary paths. Complete Search is often used when the search space is large but finite, and there are no other known algorithms that use a method other than exhaustive search.
What is recursive backtracking, and where is it commonly used?
Recursive backtracking is a type of Complete Search that involves making a series of decisions to build a recursively defined structure while ensuring that certain constraints are met. It is commonly used in problems like the N-Queens problem, Sudoku, maze-solving, and other combinatorial or constraint satisfaction problems. Recursive backtracking uses recursive calls to explore different possibilities and backtracks when a path leads to failure.
How can the N-Queens problem be solved using recursive backtracking?
The N-Queens problem can be solved using recursive backtracking by placing queens on an n x n chessboard, ensuring that no two queens attack each other. The process involves:
Representing the board as an array, where each element represents the position of a queen in a row.
Recursively placing queens on the board while checking for conflicts with previously placed queens.
Backtracking when a placement leads to conflicts, allowing the algorithm to find all possible solutions or a specific solution, depending on the requirement.
What is the template for a recursive backtracking algorithm?
The template for a recursive backtracking algorithm involves the following steps:
Check if the current state represents a solution. If it does, report success.
For every possible choice from the current state:
Make the choice and take one step along the path.
Use recursion to try to solve the problem for the new state.
If the recursive call succeeds, report success to the previous level.
If the recursive call fails, backtrack to restore the original state.
If no choices lead to a solution, report failure.
What are the advantages of recursive backtracking?
The advantages of recursive backtracking are:
It can solve complex problems by exploring all possibilities.
It is flexible and can be adapted to various problem types.
It is relatively straightforward to implement.
What are the disadvantages of recursive backtracking?
The disadvantages are:
It can be slow due to exhaustive search.
It may require a lot of memory for recursion and tracking state.
It might not be the most efficient approach for problems with large search spaces.
