Problem Statement
What is the key characteristic of backtracking algorithms?
Explanation
Backtracking explores all possible solutions by building candidates incrementally and abandoning candidates as soon as it determines they cannot lead to a valid solution. This pruning of the search tree is called backtracking.
The algorithm tries to build a solution step by step. At each step, if the current partial solution cannot possibly lead to a complete valid solution, it backtracks by removing the last choice and tries a different option. This is more efficient than brute force as it avoids exploring obviously invalid paths. Backtracking does not guarantee optimal solutions and typically has exponential time complexity.
Code Solution
SolutionRead Only
// Backtracking Template
void backtrack(solution, choices) {
// Base case: found solution
if (isSolution(solution)) {
addToResults(solution);
return;
}
// Try each choice
for (choice in choices) {
// Make choice
solution.add(choice);
// Explore with this choice
if (isValid(solution)) {
backtrack(solution, newChoices);
}
// Backtrack: undo choice
solution.remove(choice);
}
}
// Example: N-Queens
// Try placing queen in each column
// If safe, recurse to next row
// If not safe or no solution found, backtrack