His rowboat is so small that he can carry only one of them at a time, and only he can row.
If the coyote is left alone with the chicken, it eats the chicken. If the chicken is left alone with the corn, it eats the corn. Nothing gets eaten while the farmer is present.
How does he get all three across safely?
💡 Hint
Check who is left alone on each bank after every trip. At one point every forward move creates a problem, so ask whether progress ever means undoing something.
Reveal answer
Chicken over, return alone, coyote over, bring the chicken back, corn over, return alone, chicken over: 7 crossings.
Step-by-step solution
- Take the chicken across. The coyote and the corn stay behind, which is safe.
- Row back alone.
- Take the coyote across. Now the coyote and the chicken share the far bank, so the farmer can’t leave them there together.
- Bring the chicken back to the starting bank. This is the key move.
- Leave the chicken and take the corn across. The corn and the coyote are a safe pair on the far bank.
- Row back alone, then take the chicken across one last time. All three are across in 7 crossings.
- A computer search of every possible position confirms that 7 is the minimum and that there are exactly two shortest solutions: this one, and the same one with the coyote and the corn swapped.
Why it fools people
The puzzle fools people because its essential move goes against our sense of progress. Carrying the chicken back feels like undoing work, so we don’t consider it. Yet it’s the only way to separate the coyote and the chicken without leaving the chicken with the corn. The chicken clashes with everything, so it has to travel more than anyone else. Accepting a step backward to reach a better position is a lesson that goes well beyond rivers.
Did you get it?
About This Puzzle
River crossing puzzles are among the oldest recreational puzzles in the Western world, and this is the most famous of them, retold here on an American ranch. The setup is simple: a small boat, three things to ferry and two dangerous pairings. What makes it satisfying is that the obvious approach stalls halfway, and progress requires a move that feels like going backward. Grab a pencil and draw two riverbanks. Sketching each position as you go makes the puzzle far easier to track and shows you exactly where your first attempt runs into trouble.
How to Think About It
Start by finding the item that causes the most trouble. List the dangerous pairs and count how often each item appears in them. The item that clashes with both others needs the most careful handling; the two that never clash can safely wait together. Then treat the puzzle as a series of positions, each one a description of who is on which bank. A move is legal only if neither bank is left with a dangerous pair. And read the rules closely: they limit what the boat can hold, not which direction it travels.
Common Traps
Most people try each item first and give up when the second trip creates a disaster on the far bank. The hidden assumption is that every trip has to move things forward, so once something is across, it stays across. Nothing in the rules says that. A second trap is to take the coyote first because it seems most dangerous, which leaves the chicken and the corn together on the starting bank. Think about which pairs are dangerous, not which animal looks scariest.
Where This Puzzle Comes From
The oldest known version appears in a Latin collection of puzzles for young people attributed to Alcuin of York, an English scholar at the court of Charlemagne around the year 800. His version used a wolf, a goat and a cabbage. Variations have appeared in many cultures since. Computer scientists still use it to teach state space search: list every possible position, connect the ones that are one legal move apart, and look for the shortest path from start to finish.
Try This Variation
The farmer upgrades to a bigger rowboat that can carry him plus two of the three at once. The same eating rules apply on the banks, and nothing is eaten in the boat while he’s in it. What is the fewest number of crossings he needs now?
Show the answer to the variation
Three crossings. Take the coyote and the corn over together, leaving the chicken alone, which is safe. Row back alone; the coyote and the corn are a safe pair. Then bring the chicken over. One crossing can’t work because three passengers won’t fit, and two crossings would leave the farmer on the starting bank.