River Crossing River Fox Chicken Grain Medium — Set 19

Medium River Crossing Puzzle #19

Title

Medium River Crossing Puzzle #19

Scenario

Fox, Chicken & Grain

Narrative

A farmer must cross a river with a fox, a chicken, and a bag of grain. The boat can carry only the farmer and one item at a time.

Entities

• {"id":"fox","name":"Fox","icon":"\ud83e\udd8a"}
• {"id":"chicken","name":"Chicken","icon":"\ud83d\udc14"}
• {"id":"grain","name":"Grain","icon":"\ud83c\udf3e"}

BoatCapacity

1

Constraints

• The fox cannot be left alone with the chicken (the fox will eat the chicken).
• The chicken cannot be left alone with the grain (the chicken will eat the grain).
• The farmer must always be in the boat when crossing.

Question

Describe a valid sequence of crossings that gets everyone to the other side without violating any constraint. What is the minimum number of trips required?

Solution

• {"trip":1,"direction":"\u2192","carrying":["Chicken"],"leftBank":["Fox","Grain"],"rightBank":["Chicken"],"note":"Take the chicken across first."}
• {"trip":2,"direction":"\u2190","carrying":[],"leftBank":["Fox","Grain","Farmer"],"rightBank":["Chicken"],"note":"Return empty."}
• {"trip":3,"direction":"\u2192","carrying":["Fox"],"leftBank":["Grain"],"rightBank":["Chicken","Fox"],"note":"Take the fox across."}
• {"trip":4,"direction":"\u2190","carrying":["Chicken"],"leftBank":["Grain","Chicken"],"rightBank":["Fox"],"note":"Bring the chicken back."}
• {"trip":5,"direction":"\u2192","carrying":["Grain"],"leftBank":["Chicken"],"rightBank":["Fox","Grain"],"note":"Take the grain across."}
• {"trip":6,"direction":"\u2190","carrying":[],"leftBank":["Chicken","Farmer"],"rightBank":["Fox","Grain"],"note":"Return empty."}
• {"trip":7,"direction":"\u2192","carrying":["Chicken"],"leftBank":[],"rightBank":["Fox","Grain","Chicken"],"note":"Take the chicken across. Done!"}

MinimumTrips

7

Hint

The first 2 move(s) of the solution are shown below to help you start.

PartialSolutionHint

• {"trip":1,"direction":"\u2192","carrying":["Chicken"],"leftBank":["Fox","Grain"],"rightBank":["Chicken"],"note":"Take the chicken across first."}
• {"trip":2,"direction":"\u2190","carrying":[],"leftBank":["Fox","Grain","Farmer"],"rightBank":["Chicken"],"note":"Return empty."}