Simplified Solution of Zebra Puzzle or Einstein Puzzle

What was the puzzle?

Let's recollect the given clues once again.

1. There are five houses in a row. Each of the houses is painted a different color, and their occupants come from different countries, own different pets, drink different beverages, and smoke different cigarette brands.
2. The Englishman lives in the red house.
3. The Spaniard owns the dog.
4. Coffee is drunk in the green house.
5. The Ukrainian drinks tea.
6. The green house is immediately to the right (your right) of the ivory house.
7. The Old Gold smoker owns snails.
8. Kools are smoked in the yellow house.
9. Milk is drunk in the middle house.
10. The Norwegian lives in the first house.
11. The man who smokes Chesterfields lives in the house next to the man with the fox.
12. Kools are smoked in the house next to the house where the horse is kept.
13. The Lucky Strike smoker drinks orange juice.
14. The Japanese smokes Parliaments.
15. The Norwegian lives next to the blue house.

================================================================

STEP 1 :

As per clue (1), let's create a table like below, and then fill the data one by one.

================================================================

STEP 2 :

As per clue (9),(10) and (15),

================================================================

STEP 3 :

As per (2), Englishman lives in red house, that means it can't be first house. Also, (6) points that green house is next to ivory. So, ivory-green can't be at 1-2 positions. But those can be at 3-4 with red at 5 or at 4-5 with red at 3.

In short, only color left for 1 is yellow. And as per (8), Kools are smoked in the yellow house. 

=================================================================

STEP 4 :

Now as per (12), Kools are smoked in the house next to the house where the horse is kept.

=================================================================

 STEP 5 :

Let's assume the red house of Englishman is at no.5 then Ivory-Green are at no.3-4.
Since as per (4), green house owner drinks coffee, and only position left for Ukrainian drinking tea pointed by (5) is house no.2.

=================================================================

STEP 6 :

Now the luck strike smoker drinking orange juice pointed by (13) has only position and that is house no.5. That leaves only drink available for house 1 as water.

As per (3), Spaniard who owns dog has houses 3 and 4 available but for Old Gold smoker (pointed by (7)) also available houses are 3 and 4 again.

If Old Gold smoker occupies house 3 then Spaniard who own dog would have house 4. In that case, there will be no position would be left for Japanese smoking Parliaments (Clue no.14).

Same can be proved if Old Gold smoker occupies house no.4.

Hence, our assumption made in step 5 is wrong. So, Red house must be at 3 owned by Englishman.

===============================================================

STEP 7 :

So if Englishman's red house is at no.3 then at no.4 & 5 there must be ivory and green houses where coffee is drink in green house.

================================================================

STEP 8 :

Now, for Lucky Strike smoker who drinks orange juice (clue 13) and Ukrainian who drinks tea (clue 5) only available houses are (see above table) house no.2 & 4. That is, 2 and 4 are occupied by tea & orange juice drinkers (order yet unknown). With that, we can conclude that the drink in first house is Water.

==============================================================

STEP 9 : 

If we assume that Lucky Striker smoker who drinks Orange juice (clue 13) live in house no.2 then Ukrainian who drinks tea (clue 5) has to be in house no.4. With that, Japanese who smokes Parliament (clue 14) need to be in the house no.5. No house is left for Spaniard who owns the dog (clue 3) as house no.2 is already occupied by pet horse. 

That's why the Lucky Strike smoker with Orange juice as drink must be in house no.4.

================================================================

STEP 10 : 

Now, if Lucky Strike smoker (clue 13) is living in house no.4 then Ukrainian who drinks tea (clue 5) must be in house no.2. With that, Japanese who smokes Parliament (clue 15) needs to be in house no.5 and Spaniard who owns dog (clue 3) needs to be in house no.4.

===============================================================

STEP 11 :

In the end, for Old Gold smoker (clue 7) only house left is house no.3. And as per clue 11,Chasterfield smoker needs to be in the house followed by fox owner. Hence, they must be in the house no.1 and 2 respectively. Finally, the only pet left for house no.5 is Zebra.

==============================================================

CONCLUSION : 

The final table looks like - 

Now, finding answers of given questions is easy from the table.

Who drinks water? 
- Norwegion

Who owns the zebra?  
- Japanese 
 

The Story of The Indecisive Rower

A rower rows regularly on a river, from A to B and back. He’s got into the habit of rowing harder when going upstream, so that he goes twice as fast relative to the water as when rowing downstream. 

One day as he’s rowing upstream he passes a floating bottle. He ignores it at first but then gradually grows curious about its contents. After 20 minutes of arguing with himself he stops rowing and drifts for 15 minutes. Then he sets out after the bottle. After some time rowing downstream he changes his mind, turns around, and makes his way upstream again. But his curiosity takes hold once more, and after 10 minutes of rowing upstream he turns and goes after the bottle again. Again he grows ashamed of his childishness and turns around. But after rowing upstream for 5 minutes he can’t stand it any longer, rows downstream, and picks up the bottle 1 kilometer from the point where he’d passed it. 

How fast is the current?

That's the speed of water current!

Water Speed in The Story of The Indecisice Rower

What was the story?

Just for a moment let's assume the rower is rowing on a calm lake where water is stationary. Then, the bottle that he saw is also not moving & floating at one point.

In the case, he moves away (upstream in real case) from the bottle & comes back (downstream in real case) again to collect the bottle. He rows away from the bottle for 20 + 10 + 5 = 35 minutes. 

Remember his speed is double when he goes away from bottle than when he is coming towards the bottle. That's why he takes 35 X 2 = 70 minutes to come back at the point where bottle is floating.

Moreover, he drifts for 15 minutes in real case; for that let's assume he sits motionless for 15 minutes (in our assumed lake case) at some point in between.

So after leaving the bottle, he returns to the bottle after 35 + 15 + 70 = 120 minutes.

Now, assume this water in the lake is moving and this bottle is 'displaced' by 1 KM away from it's original position in 120 minutes. 

That means, the water is moving at the speed of 1 km / 120 minutes. That is the speed of water current is 1/2 kmph.  

"Share The Walk; Share The Ride!"

You and I have to travel from Startville to Endville, but we have only one bicycle between us. So we decide to leapfrog: We’ll leave Startville at the same time, you walking and I riding. I’ll ride for 1 mile, and then I’ll leave the bicycle at the side of the road and continue on foot. When you reach the bicycle you’ll ride it for 1 mile, passing me at some point, then leave the bicycle and continue walking. And so on — we’ll continue in this way until we’ve both reached the destination.

Will this save any time? 

You say yes: Each of us is riding for part of the distance, and riding is faster than walking, so using the bike must increase our average speed.

I say no: One or the other of us is always walking; ultimately every inch of the distance between Startville and Endville is traversed by someone on foot. So the total time is unchanged — leapfrogging with the bike is no better than walking the whole distance on foot.

Who’s right?

Look who is right in the case!