Logic training - Einstein's reasoning questions

The purpose of writing this series is to keep the brain thinking, not to rust!

The content of the topic is as follows:

On the street of a small town, there are five rooms with five different colors. A person of a different nationality lives in each room; everyone drinks a particular beverage; smokes a particular brand of cigarettes; owns a particular pet; no two people smoke the same brand of cigarettes, or drink the same the same brand of beverage, or having the same pets. Einstein gave the following clue:

1. The Englishman lives in the red house;
2. Swedes keep dogs;
3. Danes drink tea;
4. The green house is next to the white house, to the left of the white house;
5. Green house owner drinking coffee;
6. People who smoke PM cigarettes keep birds;
7. People in the yellow house smoke DH brand cigarettes;
8. Those who live in the middle house drink milk;
9. The Norwegian lives in the first house (far left);
10. The person who smokes Blends is next to the person who owns cats;
11. The man who raises horses is next to the man who smokes DH cigarettes;
12. Those who smoke BM drink beer;
13. Germans smoke Prince cigarettes;
14. Norwegians live next to those who live in blue houses;
15. The person who smokes Blends is next to the person who drinks mineral water.

Q: Who is keeping the fish? It is claimed that only 2% of people can answer this question. Blow, just blow! This question is step-by-step, and everyone can reason it out. Let's sort out the clues first:

• Nationality: British, Swedish, Danish, German, Norwegian
• House: red, green, white, yellow, blue
• Drinks: tea, coffee, milk, beer, mineral water
• Pets: Dogs, Birds, Cats, Horses, Fish
• Cigarettes: PM, BM, Blends, Prince, DH

According to conditions 1 (British people live in red houses), 2 (Swedes keep dogs), 3 (Danish people drink tea), and 13 (Germans smoke Prince cigarettes), the following table can be constructed first, and then the table can be continuously improved by reasoning.

	house	pet	drinks	cigarette
U.K.	red
Sweden		dog
Denmark			Tea
Germany				Prince
Norway

Looking at this list, I feel that there are too many vacancies. So let's start deriving step by step.

• Regarding the order of the houses, let me say the conclusion first: yellow-blue-red-green-white, Norwegians live in yellow houses, and British people drink milk. The reasoning process is as follows:
  • According to conditions 9 (Norwegians live in the first house) and 14 (Norwegians live next to people who live in the blue house), the blue house must be the second; because the Norwegian lives on the far left, the red house of the British must be Not the first room.
  • According to condition 4 (the green house is next to the white house, on the left side of the white house), the green house is definitely not the first house, if it is the first house, then the white house is next to it to the right and becomes the second house, Contradicts with the above.
  • According to the previous reasoning, neither the green house nor the red house is the first house, and the second house is the blue house (because the white house is next to the green house on the right, so it must not be the second house.), it is concluded that the first house It must be the yellow house. The possible arrangements at this time are: 1) yellow blue-red-green white; 2) yellow blue-green white-red.
  • According to conditions 5 (the owner of the green house drinks coffee) and 8 (the person who lives in the middle house drinks milk), so if the arrangement is "yellow blue-green white-red", the green house is in the middle, which is contradictory to the person who lives in the middle and milk . So the order must be "yellow blue-red-green white". Because the British live in a red house, and the red house is in the middle, so the British drink milk.
• Because Norwegians live in yellow houses, according to condition 7 (people in yellow houses smoke DH brand cigarettes), Norwegians smoke DH brand cigarettes.
• Because the cigarettes (Prince, DH) of the Germans and Norwegians have been determined, the cigarettes smoked by the British, Swedish and Danish people may be PM, and BM drinks Blends. According to condition 12 (the person who smokes BM cigarettes drinks beer), since the Danes drink tea and the English drink milk, it is only possible that the Swedes smoke BM cigarettes and drink beer.

Well, based on the reasoning above, we can update the table and fill in more useful information (yellow -1 means the first house on the left is yellow).

	house	pet	drinks	cigarette
U.K.	Red-3		milk
Sweden		dog	beer	BM
Denmark	THE		Tea
Germany	LV		KF	Prince
Norway	yellow-1		S	DH

• Germans and Norwegians can only choose coffee and mineral water as beverages. According to condition 5 (the owner of the green house drinks coffee), Norwegians drink mineral water, while Germans drink coffee and live in green houses.
• According to condition 11 (the person who raises horses is adjacent to the person who smokes DH brand cigarettes), because the Norwegian smokes DH and lives in the first room on the far left, the neighbor can only be in the second room, and because of condition 14 (Norwegians adjacent to the person who lives in the blue house), then the person who raises horses lives in the blue house.
• According to condition 15 (the person who smokes Blends is adjacent to the person who drinks mineral water), plus the result of the reasoning above, the person who lives in the blue house raises horses and smokes Blends.
• According to known reasoning results, the brands of cigarettes smoked by the British and Danes may be PM and Blends. Based on the results of the above reasoning, people who smoke Blends live in blue houses, and British people who live in red houses can only smoke PM brand cigarettes, so Danes live in blue houses and raise horses. By the way, it can also be concluded that the Swedes live in white houses.

Let's update the table again.

	house	pet	drinks	cigarette
U.K.	Red-3		milk	PM
Sweden	white-5	dog	beer	BM
Denmark	Blue-2	horse	Tea	Blends
Germany	Green-4		coffee	Prince
Norway	yellow-1		water	DH

Now we are very close to the goal, continue!

• According to condition 6 (the person who smokes PM keeps birds), the British keep birds.
• According to condition 10 (the person who smokes Blends is adjacent to the person who owns cats), the German smokes Blends, the Norwegian is on the left, and the British is on the right. Because the British have birds, the Norwegians have cats .
• Answer: The Germans keep fish!

The final result is as follows:

	house	pet	drinks	cigarette
U.K.	Red-3	bird	milk	PM
Sweden	white-5	dog	beer	BM
Denmark	Blue-2	horse	Tea	Blends
Germany	Green-4	fish	coffee	Prince
Norway	yellow-1	Cat	water	DH