ขนสินค้าข้ามฟาก

Sources & notes

1. "River crossing puzzle," Wikipedia, a logic puzzle whose object is to carry items from one river bank to the other, usually in the fewest trips; the difficulty comes from restrictions on which or how many items can be transported at once, or which or how many may be safely left together (in the classic variant a goat and vegetables cannot be left alone together); well-known versions include the wolf/goat/cabbage problem, the missionaries and cannibals puzzle (also called the jealous husbands problem), and the bridge and torch problem; and the earliest known river-crossing problems appear in the "Propositiones ad Acuendos Juvenes" attributed to Alcuin, with copies dating from the 9th century. en.wikipedia.org/wiki/River_crossing_puzzle.
2. "Wolf, goat and cabbage problem," Wikipedia, a farmer with a wolf, a goat, and a cabbage must cross a river in a boat that can carry only the farmer and a single item; the wolf cannot be left unattended with the goat, nor the goat with the cabbage, or one will eat the other; the puzzle dates back to at least the 9th century AD from a manuscript by Alcuin of York and has entered the folklore of several cultures; and the key insight is that the farmer can bring things back, giving a solution of seven crossings. en.wikipedia.org/wiki/Wolf,_goat_and_cabbage_problem.
3. River Reckoning game engine: a generalized river-crossing puzzle in which you ferry four to six cargo items across a river, with two to four forbidden pairs that may never be left alone together on a bank; because the ferryman attends only the boat's side, the safety test is applied to the boat-free bank alone; the boat's capacity changes each crossing with the tide, cycling through a short repeating pattern of one- and two-item loads, so ordering matters, and the ferryman may row back alone (the empty crossing), though an empty trip away from the starting bank is refused; a position is the item set on each bank plus the boat side and the crossing count, a crossing carries the loaded items and flips the boat, and the goal is every item on the right with the boat on the right; one forbidden pair is hidden from the rules line until the player first strands it. The engine runs a bounded breadth-first search to find the minimal number of crossings (the par), to validate solvability, and to generate solvable seeded puzzles, all pure and deterministic. Read from the game's own source.