# Puzzle | Couples crossing the river

• Difficulty Level : Medium
• Last Updated : 26 Aug, 2017

Three couples are on the vacation.They need to cross the river to reach their hotel. There are 3 rules which are as follows:-
Rule 1:- The boat can only carry two people at a time. If the third person trying to get in the boat then the boat will sink.
Rule 2:- The husbands are so jealous that they can not let their wife with another man, without their presence.
Rule 3:- The boat cannot run on itself. At-least one person should be on the boat to go from one side to another.

How many trips does it take them to all get across the river?
Note:The couples can be identified by their matching color clothes and there is no other way of going to hotel.

Solution:

Let the 3 couples have wore green, red and blue dresses.So, there should be green wife and green husband, red wife and red husband, blue wife and blue husband.
Step 1:-Green couple will go to the hotel side and green husband will return with the boat.(2 moves)
Step 2:-Now red wife and blue wife will go to the hotel side and red wife will return with the boat.(2 moves)
Step 3:-Green husband and blue husband will go to the hotel side and blue couple will return with the boat.(2 moves)
Step 4:-Red husband and blue husband will go to the hotel side and green wife will return with the boat.(2 moves)
Step 5:-Red wife and blue wife will go to the hotel side and blue wife will return with the boat.(2 moves)
Step 6:-Finally, blue wife and red wife will go the hotel side.(1 move)

So, there will be a total of 11 steps.

This article is contributed by Roshni Agarwal. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.