[Algorithm][Template] Backtracking

Backtracking 전용 template

Type backtrack(candidate) {

    if find_solution(candidate):
        output(candidate)
        return
    
    // iterate all possible candidates.
    for next_candidate in list_of_candidates:
        if is_valid(next_candidate):
            // try this partial candidate solution
            place(next_candidate)
            // given the candidate, explore further.
            backtrack(next_candidate)
            // backtrack
            remove(next_candidate)

}