lib/algo/legacy/permutations.viv

# Generated by tools/algo/legacy.py from the corpus: do not edit.
# TheAlgorithms' all_permutations.py backtracking (backtracking.viv).
# Element comparisons are routed through lib/algo/legacy/order.viv; nothing else changes.
import algo.legacy.order

# from study/idioms/thealgorithms-python/backtracking.viv: create_state_space_tree generate_all_permutations

#| all_permutations.py create_state_space_tree: extend the current sequence by each
#| unused item, recurse, then undo. Python appends to and pops a list; here position
#| `index` of a fixed-length array is overwritten. Returns how many it printed.
def create_state_space_tree(sequence: Arr, current: Arr, index, used: Arr, as_text: Bool) {
    if index == len(sequence) {
        if as_text {
            text(current)
        }
        else {
            show current
        }
        return 1.0
    }
    count = 0.0
    for i to len(sequence) {
        if used[i] == 0.0 {
            current[index] = sequence[i]
            used[i] = 1.0
            count += create_state_space_tree(sequence, current, index + 1.0, used, as_text)
            used[i] = 0.0
        }
    }
    return count
}

def generate_all_permutations(sequence: Arr, as_text: Bool) {
    n = len(sequence)
    return create_state_space_tree(sequence, zeros(n), 0.0, zeros(n), as_text)
}