Questions tagged [river-crossing]
For questions regarding how to get items or people across something obeying a set of rules.
49 questions
72
votes
2
answers
3k
views
Escape across the floorboards
A mad lexophile sits alone in his apartment obsessively rearranging his Scrabble tiles and writing words on every available surface, even filling each floorboard with a word. The Scrabble tiles have ...
- 14k
33
votes
2
answers
3k
views
The cat exchanges places with a drawing of the cat
Given
CAT RENDERING
see if you can get them to exchange places, resulting in
RENDERING CAT
by ...
- 14k
32
votes
4
answers
22k
views
Learning to Solve a River Crossing Puzzle
I have seen many variations of the following puzzle:
Once upon a time, a farmer went to the market and purchased a fox, a goose, and a bag of beans. On his way home, the farmer came to the bank of ...
- 3,650
20
votes
7
answers
4k
views
Ali Baba and the 10 thieves
EDIT: This puzzle originates from the "International Mathematics Tournament of the Towns", and was published in the book "S.M.A.R.T circle overview" by Professor Andy Liu. The author has (albeit a ...
- 5,363
20
votes
1
answer
2k
views
Farmer needs to get his word across the river
In the spirit of the classic river-crossing puzzles:
...
- 14k
17
votes
2
answers
1k
views
An overcomplicated Boat Puzzle
Based on Xkcd's Boat Puzzle
At the riverbank, a succession of people have given you a large lump of objects to transport across the river. These are:
101 cabbages
2 goats, one of which eats wolves
4 ...
- 1,573
17
votes
2
answers
1k
views
numbers want to cross a river, but their sum must be a square number
In the world of numbers, numbers 1 to 9 want to cross a river,
They have a boat which can take 1 to 3 numbers,
But sum of the numbers must be a square number.
The boat can not sail back itself, so ...
- 18k
17
votes
4
answers
49k
views
Strategy to solve the Missionaries and Cannibals problem
In the Missionaries and Cannibals problem:
Three missionaries and three cannibals must cross a river using a boat which can carry at most two people, under the constraint that, for both banks and ...
- 1,279
13
votes
1
answer
9k
views
Fastest way to cross a river: four people with different rowing speeds
This problem is commonly cited as a Microsoft interview problem, although I have paraphrased it here to involve a river and a boat instead of a bridge and a flashlight, and tweaked the crossing times ...
user88
12
votes
10
answers
2k
views
Another river with some extra letters
2 men are at a river. There is a boat. It holds only one person at a time.
They both cross the river and continue their way...
How?
P.S. No Uber, helicopters, bridges, ropes, or anything else close ...
- 245
11
votes
2
answers
818
views
What is the maximum number of items in a river crossing puzzle?
A River Crossing puzzle puts limits on the number of items that may cross a boundary, with limits on what may be left together. The "Fox, goose and bag of beans" is one of the earliest examples. Of ...
- 1,005
11
votes
2
answers
667
views
Nothing but pairs of a kind
The objective is to reduce a given word to nothing in a series of steps.
At each step, remove every occurrence of an adjacent pair of letters of your choosing.
For example:
Problem: Reduce ...
- 14k
11
votes
1
answer
388
views
Don't look back, crazy clown
Start with these two words
INSANE RETROSPECT
and see if you can get them to exchange places by transferring one letter at a time. With each ...
- 14k
10
votes
5
answers
16k
views
River Crossing Puzzle
There is a family which contains 4 members: Dad, Mom, Son, Daughter. They have a boat which carries only 100 kg at a time. Mom and Dad weigh 100 kg each, while Son and Daughter weigh 50 kg each.
...
- 281
10
votes
2
answers
325
views
Missing lattes and mutually mistrustful words
It's always amusing to watch two kids who don't trust each other swap baseball cards by exchanging them at exactly the same moment. Words can be equally mistrustful about trading their letters. ...
- 14k
9
votes
3
answers
3k
views
$n$ couples crossing a river
There are $n$ couples on one side of the river. Nobody is on the other side. They have a boat that accommodates up to 2 people. For every trip across, someone(s) must bring the boat back as well. The ...
- 7,196
8
votes
4
answers
7k
views
Quick!!! You got only 30 seconds
There are two checkpoints on a road namely Pt. A and Pt. B. There are 5 persons standing at the Pt. A namely P , Q , R , S, T. They have a car such that P , Q , R , S , T can travel to Pt. B in 1 , 3 ,...
- 5,363
8
votes
2
answers
1k
views
Numbers nonexistent
This problem is one of the hardest problems I have ever encountered.
If you don't trust links, here it is:
There are some Couples wanting to cross a river by a boat. The boat can carry at most 3 ...
- 3,655
7
votes
3
answers
228
views
can all the dwarfs cross the river?
One hundred dwarfs weighing 1, 2, ..., and 100 kg are located on the left side of a river. They cannot swim. There is also a boat on the same side of the river with a capacity of 100 kg. Each dwarf ...
7
votes
2
answers
982
views
Cross the river with a small (4 spaces) boat
Giant, Slimy, Boy, Romy and Fatty want to cross a river.
To cross the river there is a small boat.
The boat only has 4 spaces. Every one can row the boat.
At the boat, Giant needs 4 spaces.
Slimy ...
- 18k
6
votes
3
answers
2k
views
Zombie horde incoming! [duplicate]
Here is a puzzle I found on youtube's Ted-ed channel and found quite fun to solve.
You and 3 more people are for some reason running away from a horde of zombies in the darkness while holding a ...
- 9,870
6
votes
4
answers
4k
views
Can you solve this Bruce Wayne logic puzzle?
This variation of the classical Farmer Goat puzzle was in a puzzle contest at my college two years ago.
Here it goes.
Mr. Bruce Wayne is very fond of parties. Well, he’s more fond of girls, but, ...
- 7,292
6
votes
2
answers
224
views
River crossing cats and dogs
A farmer and his $n$ cats and $m$ dogs are on one side of a river. There is a boat that can carry the farmer and at most $k$ animals at once. The boat doesn't move without a person operating it. The ...
- 17.3k
5
votes
3
answers
482
views
$n$ monsters and $n$ people
There are $n$ monsters (M) and $n$ people (P) on the left side of a river. Nobody is on the right.
They have a boat that can hold up to 2 beings. At no point on time may either of these be true:
$$M_{...
- 7,196
5
votes
2
answers
220
views
Triple up, pair off, and single out
Can you transform this word triple
PELTS SORES DIVAN
into this word triple
PLOTS DIVES SANER
just by swapping pairs of ...
- 14k
5
votes
3
answers
5k
views
When do missionaries and cannibals problems have solutions?
In the Missionaries and Cannibals problem:
Three missionaries and three cannibals must cross a river using a boat
which can carry at most two people, under the constraint that, for
both banks, ...
- 51
5
votes
1
answer
239
views
Uncover Lenny Fingers' street hustle
Lenny Fingers is out on the street again, hustling people with his shell games. This time, he's using words.
As you walk by, Lenny grabs you with an enthusiastic smile and shows you two words side-...
- 14k
5
votes
1
answer
477
views
Family river-crossing
A family of six is crossing a river with a 2-passenger boat. The family includes the following members: Dad, Mom, Maid, Boy, Girl & Dog. Only the 3 adults can row the boat and the dog counts as a ...
- 51
4
votes
5
answers
20k
views
How can the animals get across the river without a fight breaking out?
There are three dogs and three cats that have to be transported across a river: a big dog, a medium dog and a small dog, a big cat, a medium cat, and a small cat.
Rules:
The raft can carry two ...
- 369
4
votes
2
answers
1k
views
Boat children and army crossing the river puzzle
During the war, a small detachment found itself
confronted by a deep and wide river. However, they found a small boat in which
two-children were rowing about. It was a very small boat and can only ...
- 1,056
4
votes
1
answer
204
views
A frugal canal-crossing
You've been sent out to round up some escaped animals. While you have some of them under control now, you've ended up trapped on the wrong side of a canal. Currently, you have 5 animals:
A perivine, ...
- 1,573
4
votes
1
answer
206
views
Terrorists transporting Hostages through the desert
You belong to an intelligence agency that is monitoring some terrorists. There are three of them in the Hideout A with three hostages and a bomb. Unfortunately, this hideout is extremely secure. But ...
- 1,615
3
votes
3
answers
213
views
A small pond-crossing
While walking through the flower gardens, you encounter a small group of fairies stuck on a lilypad. There are 2 red fairies, 2 yellow fairies, and 2 green fairies, and they have nothing besides a ...
- 1,573
3
votes
1
answer
180
views
Crossing a river with bonds and beefs
Here is a river crossing puzzle (note that whenever I use the term "colors", I mean the squares):
Yellow and Red are on one side of the river, while Pink, Blue, Green and Black are on the ...
- 13.2k
3
votes
1
answer
673
views
Rigorous way to solve the river crossing problem
I encountered this classic brain teaser:
Four people, A, B, C and D need to get across a river. The only way to
cross the river is by an old bridge, which holds at most 2 people at a
time. ...
- 131
2
votes
2
answers
6k
views
The case of the 4 campers and the rickety bridge! [duplicate]
Four people need to cross a rickety rope bridge to get back to their camp at night. Unfortunately, they only have one flashlight and it only has enough battery left for seventeen minutes. The bridge ...
- 2,292
2
votes
2
answers
306
views
A river crossing puzzle
Here is a puzzle I came up with.
Ali and Billie are approaching a river from one side, and Casey and Devin from the other side.
Ali shouts: "Do you two also want to cross?"
Casey shouts back:...
- 201
2
votes
1
answer
222
views
Crossing desert with smallest amount of water [duplicate]
A man who lives in a desert sends his servant out to collect the flag which is 4 miles away from the man's home. To survive the servant must drink 1 litre of water on every mile he walks (so the ...
- 29
1
vote
4
answers
287
views
How do I find the least number of times a shuttle can travel from one place to another?
I often see this situation in exams and I'd like to know if there is any kind of algorithm or shortcut that I can use to solve this puzzle instead of just guessing.
The problem is as follows:
A space ...
- 1,581
1
vote
2
answers
2k
views
3 cannibals and 3 missionaries on different side of the river
Three missionaries on the left side of a river and three cannibals on the right side of the river want to cross a river using a boat which can carry at most two people, The boat is on the cannibals ...
- 18k
1
vote
2
answers
1k
views
Crossing The River (Humans And Monsters Puzzle With A Twist)
3 couples on one side of a river. Aa Bb Cc (caps representing husbands, lowercase representing wives)
One boat in which 2 people can travel at a time.
At least one person must row the boat wherever ...
- 319
0
votes
1
answer
302
views
Strait-Crossing Puzzle
You are on an island, and must transport 3 moose across a strait to the mainland. While they can swim across the strait, they will likely end up running into the forest and leaving you behind. While ...
- 1,573
0
votes
2
answers
316
views
Wounded Soldiers/Crossing a Bridge Puzzle - checking a solution
I am working on a Prolog university assignment, where we have to determine what the shortest time is for 4 wounded soldiers to cross a bridge to safety. This seems to be a variation of the more common ...
0
votes
2
answers
177
views
Minimum time to cross the bridge
There are 6 friends A, B, C, D, E and F who want to cross a bridge. However, there are two problems. First, the bridge can only accommodate two persons at a time. Second, it is night and they need the ...
-1
votes
1
answer
910
views
A Fox, a Chicken, a Pile of Seeds, and a Boat [duplicate]
There's 2 islands, 1 island has a pile of seeds, a chicken, and a fox. There's also a boat next to this island, you have to get it all across with minimum uses of the boat. You can only take one ...
- 14.6k
-1
votes
1
answer
13k
views
A man, a chicken, and a fox? [duplicate]
A man lives in a small house with a farm as his back garden and has a river beside his house. On the other side of the river is a shop. One day, he visited the shop, he bought a chicken and a fox for ...
- 101
-2
votes
2
answers
2k
views
Bridge's riddle [duplicate]
You're in a group of people going for an internship in a remote mountain lab. By mistake you pulled a lever with a skull just out of curiosity and it released some zombies. So you and your group had ...
-4
votes
1
answer
4k
views
How can the man get across the river with the two animals and the cabbage? [duplicate]
A man has a wolf, a goat, and a cabbage. He must cross a river with the two animals and the cabbage. There is a small rowing boat, in which he can take only one thing with him at a time. If, however, ...
user5049
-4
votes
1
answer
202
views
Ancient mysteries of the Arab world [duplicate]
If we want to convey the lion and the sheep and feed from the bank of the river to the other how to do it?
and the lion will not eat the sheep and the sheep will not eat the feed
- 11