The backtracking algorithm design approach is a problem-solving technique that systematically explores all possible solutions to a problem by incrementally building a solution candidate and backtracking when it determines that the current candidate cannot be extended to a valid solution.
The backtracking approach typically involves the following steps:
1. Define the Problem Space: Clearly define the problem and its constraints. Identify the decision variables, the goal, and any additional constraints or conditions that must be satisfied.
2. Choose a Search Space Representation: Determine how to represent the search space or the possible solutions to the problem. This representation could be a tree, a graph, an array, or any other data structure suitable for the problem.
3. Construct a Solution Candidate: Start building a potential solution by making choices or selecting values for the decision variables. Each choice will lead to a new candidate solution.
4. Validate the Solution Candidate: Check if the current candidate satisfies all the constraints and conditions imposed by the problem. If the candidate is valid and meets the desired goal, a solution is found. Otherwise, move to the next step.
5. Explore and Iterate: If the current candidate is invalid, backtrack to the previous decision point and explore alternative choices or values. This involves undoing the last choice and moving to the next option. Repeat this process recursively until all possible candidates have been explored.
6. Termination Condition: Define a termination condition that determines when the search process should stop. This condition could be reaching a specific depth in the search space, exhausting all possible choices, or finding the desired number of solutions.
When to Apply: The backtracking approach allows for an exhaustive search of the solution space, systematically exploring all possible candidates. It is particularly useful when the problem involves finding all valid solutions or when an optimal solution needs to be found. However, it can be computationally expensive for large search spaces, so optimizations such as pruning or constraint propagation may be necessary.
Common examples of problems solved using the backtracking approach include the N-Queens problem, Sudoku, and solving mazes. In each case, the backtracking algorithm explores all possible configurations until a valid solution is found or all possibilities are exhausted.
The links below open Jupyter Notebook pages on Google Colab (https://colab.research.google.com/) and present how to solve the corresponding computer science problem using the Backtracking algorithmic design approach.
List of computer science problems that can be solved using the Backtracking Approach:
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