Page Title

CONDITIONS:

There are five houses.
The Mathematician lives in the red house.
The Hacker writes in Python.
Brackets (code editor) is used in the green house.
The Analisyst uses Atom (code editor).
The green house is immediately to the right of the ivory house.
The man who uses Redis (Database System) writes in Java.
Cassandra (Database System) is used in the yellow house.
Notepad++ (code editor) is used in the middle house.
The Developer lives in the first house.
The man who uses Hadoop (Database System) lives in the house next to the man writing in Javascript.
Cassandra is used in the house next to the house where the primary language is C#.
The man who uses ArangoDB uses Sublime Text (code editor).
The Engineer uses MongoDB.
The Developer lives next to the blue house.

Now, who uses Vim? Who writes in C++?

Colors of houses (ch)

red (r)
green (g)
ivory (i)
blue (b)
yellow (y)

Professions (pr)

Mathematician (m)
Hacker (h)
Analisyst (a)
Developer (d)
Engineer (e)

Coding languages (cl)

Python (p)
Java (j)
Javascript (js)
C# (cs)
C++ (cpp)

Core editors (ce)

Brackets (b)
Atom (a)
Notepad++ (n)
Sublime Text (st)
Vim (v)

Database systems (ds)

Redis (r)
Cassandra (c)
Hadoop (h)
ArangoDB (a)
MongoDB (m)

ch	r g i b y	r g i b y	r g i b y	r g i b y	r g i b y
pr	m h a d e	m h a d e	m h a d e	m h a d e	m h a d e
cl	p j js cs cpp	p j js cs cpp	p j js cs cpp	p j js cs cpp	p j js cs cpp
ce	b a n st v	b a n st v	b a n st v	b a n st v	b a n st v
ds	r c h a m	r c h a m	r c h a m	r c h a m	r c h a m

The first condition is already fulfilled. (14 left)

Conditions 9 (Notepad++ (code editor) is used in the middle house.) and 10 (The Developer lives in the first house.) can be fulfilled very easily.(12 left) Now the table looks like this:

ch	r g i b y	r g i b y	r g i b y	r g i b y	r g i b y
pr	Developer	m h a e	m h a e	m h a e	m h a e
cl	p j js cs cpp	p j js cs cpp	p j js cs cpp	p j js cs cpp	p j js cs cpp
ce	b a st v	b a st v	Notepad++	b a st v	b a st v
ds	r c h a m	r c h a m	r c h a m	r c h a m	r c h a m

Since the Developer lives in the first house, from condition 15 (The Developer lives next to the blue house.) we know that the blue house is the second one. (11 left) Now the table looks like this:

ch	r g i y	blue	r g i y	r g i y	r g i y
pr	Developer	m h a e	m h a e	m h a e	m h a e
cl	p j js cs cpp	p j js cs cpp	p j js cs cpp	p j js cs cpp	p j js cs cpp
ce	b a st v	b a st v	Notepad++	b a st v	b a st v
ds	r c h a m	r c h a m	r c h a m	r c h a m	r c h a m

From condition 2 we can deduce that the mathematician does NOT live in the second house since the second house is blue and the first house is NOT red because the Developer lives there.

From condition 4 we can see that Brackets are NOT used in the second house for the same reason above.

From codition 3 we can deduce that Python is NOT used in the first house since there lives the Developer.

From codition 5 we can see that Atom is NOT used in the first house since there lives the Developer and the Analisyst doesn't live in the middle house because the man living there uses Notepadd++.

From condition 6 we are able to remove the variant the first house to be ivory because the house to the right is blue and the third house is NOT green because the house to the left isn't ivory but blue.

From codition 8 we can deduce that Cassandra is Not used in the second house because the house is blue.

From condition 13 we can see that ArangoDB is NOT used in the middle house because there is used Notepad++.

From condition 14 we can deduce that MongoDB is NOT used in the first house because the Developer lives there.

Sorry for the repetition, I didn't come up with better way of writing everything.

Now the table looks like this:

ch	g y	blue	r i y	r g i y	r g i y
pr	Developer	h a e	m h e	m h a e	m h a e
cl	j js cs cpp	p j js cs cpp	p j js cs cpp	p j js cs cpp	p j js cs cpp
ce	b st v	a st v	Notepad++	b a st v	b a st v
ds	r c h a	r h a m	r c h m	r c h a m	r c h a m

The first house is NOT green because if it is, then there is not house to the left, but fro condition 6 we know that the house left of green is ivory. So the first house is yellow. The last house is NOT ivory for the same reason.

ch	yellow	blue	r i	r g i	r g
pr	Developer	h a e	m h e	m h a e	m h a e
cl	j js cs cpp	p j js cs cpp	p j js cs cpp	p j js cs cpp	p j js cs cpp
ce	b st v	a st v	Notepad++	b a st v	b a st v
ds	r c h a	r h a m	r c h m	r c h a m	r c h a m

So the Developer uses Cassandra since he lives in the yellow house. So condition 8 is fulfilled. (10 left)

ch	yellow	blue	r i	r g i	r g
pr	Developer	h a e	m h e	m h a e	m h a e
cl	j js cs cpp	p j js cs cpp	p j js cs cpp	p j js cs cpp	p j js cs cpp
ce	b st v	a st v	Notepad++	b a st v	b a st v
ds	Cassandra	r h a m	r h m	r h a m	r h a m

Since Cassandra is used in the first house, according to condition 12, C# is used in the second house (9 left) and according to condition 7, the Developer does NOT write in Java.

ch	yellow	blue	r i	r g i	r g
pr	Developer	h a e	m h e	m h a e	m h a e
cl	js cpp	C#	p j js cpp	p j js cpp	p j js cpp
ce	b st v	a st v	Notepad++	b a st v	b a st v
ds	Cassandra	r h a m	r h m	r h a m	r h a m

Because the Hacker writes in Python, he does NOT live in the second house. The Developer is NOT usig Brackets because he lives in the yellow house. The man living in the second house does NOT use Redis because he writes in C#.

ch	yellow	blue	r i	r g i	r g
pr	Developer	a e	m h e	m h a e	m h a e
cl	js cpp	C#	p j js cpp	p j js cpp	p j js cpp
ce	st v	a st v	Notepad++	b a st v	b a st v
ds	Cassandra	h a m	r h m	r h a m	r h a m

Since the developer uses Cassandra, not ArangoDB, he does NOT use Sublime Text, so his core editor is Vim.

ch	yellow	blue	r i	r g i	r g
pr	Developer	a e	m h e	m h a e	m h a e
cl	js cpp	C#	p j js cpp	p j js cpp	p j js cpp
ce	Vim	a st	Notepad++	b a st	b a st
ds	Cassandra	h a m	r h m	r h a m	r h a m

Now we got to dead end. We cannot continue to solve it logically, so we have to guess. Let's try the language of the developer because they are only two options. If he writes in C++, the answer to both questions is the Developer. It can be but it doesn't look true plus we have to complete the whole table somehow. Ok, let's try the other option.

ch	yellow	blue	r i	r g i	r g
pr	Developer	a e	m h e	m h a e	m h a e
cl	Javascript	C#	p j cpp	p j cpp	p j cpp
ce	Vim	a st	Notepad++	b a st	b a st
ds	Cassandra	h a m	r h m	r h a m	r h a m

Now, according to condition 11, in the second house is used Hadoop.

ch	yellow	blue	r i	r g i	r g
pr	Developer	a e	m h e	m h a e	m h a e
cl	Javascript	C#	p j cpp	p j cpp	p j cpp
ce	Vim	a st	Notepad++	b a st	b a st
ds	Cassandra	Hadoop	r m	r a m	r a m

Condition 13 tels us that that the man living in the second house isn't using Sublime Text, so he is using Atom as core editor. And then condition 5 tels us that the man is the Analisyst. Now the table looks like this:

ch	yellow	blue	r i	r g i	r g
pr	Developer	Analisyst	m h e	m h e	m h e
cl	Javascript	C#	p j cpp	p j cpp	p j cpp
ce	Vim	Atom	Notepad++	b st	b st
ds	Cassandra	Hadoop	r m	r a m	r a m

The forth house can't be red because then the green one and the ivory one will be disconnected which cannot happen.

ch	yellow	blue	r i	g i	r g
pr	Developer	Analisyst	m h e	m h e	m h e
cl	Javascript	C#	p j cpp	p j cpp	p j cpp
ce	Vim	Atom	Notepad++	b st	b st
ds	Cassandra	Hadoop	r m	r a m	r a m

Now, unfortunately, we are in another dead end and we have to guess. I know, two guesses are a little bit suspicious but... So let's try. Now the houses are arranged in a way that if we guess one, we uncover all of them. So let's try red. Let's say that the last house is red.

ch	yellow	blue	ivory	green	red
pr	Developer	Analisyst	m h e	m h e	m h e
cl	Javascript	C#	p j cpp	p j cpp	p j cpp
ce	Vim	Atom	Notepad++	b st	b st
ds	Cassandra	Hadoop	r m	r a m	r a m

Now we know where the mathematician is from condition 2.

ch	yellow	blue	ivory	green	red
pr	Developer	Analisyst	h e	h e	Mathematician
cl	Javascript	C#	p j cpp	p j cpp	p j cpp
ce	Vim	Atom	Notepad++	b st	b st
ds	Cassandra	Hadoop	r m	r a m	r a m

And that Brackets is used in the green house. So the Mathematician uses Sublime Text

ch	yellow	blue	ivory	green	red
pr	Developer	Analisyst	h e	h e	Mathematician
cl	Javascript	C#	p j cpp	p j cpp	p j cpp
ce	Vim	Atom	Notepad++	Brackets	Sublime Text
ds	Cassandra	Hadoop	r m	r a m	r a m

From condition 13 we can deduce that the Mathematician uses ArangoDB since he uses Sublime Text. Now he doesn't use Python because he isn't the Hacker and he doesn't use Java since he doesn't use Redis. So he uses C++.

ch	yellow	blue	ivory	green	red
pr	Developer	Analisyst	h e	h e	Mathematician
cl	Javascript	C#	p j	p j	C++
ce	Vim	Atom	Notepad++	Brackets	Sublime Text
ds	Cassandra	Hadoop	r m	r m	ArangoDB

Now we have answered our initial questions. The Developer uses Vim and the Mathematician uses C++. But let's see if we can complete the table. Now it looks like this:

ch	yellow	blue	ivory	green	red
pr	Developer	Analisyst	h e	h e	Mathematician
cl	Javascript	C#	p j	p j	C++
ce	Vim	Atom	Notepad++	Brackets	Sublime Text
ds	Cassandra	Hadoop	r m	r m	ArangoDB

Now we have to make a third guess. Now everything looks really suspicious. And it is. If you try to complete the table, you will find out that there is a condradiction. The engineer has to use MongoDB from codition 14 and Redis, because the Hacker uses Python, so he has to use Java and condition 7 applies. So... the guess that the fifth house is red is wrong. So the middle one has to be red.

ch	yellow	blue	red	ivory	green
pr	Developer	Analisyst	m h e	m h e	m h e
cl	Javascript	C#	p j cpp	p j cpp	p j cpp
ce	Vim	Atom	Notepad++	b st	b st
ds	Cassandra	Hadoop	r m	r a m	r a m

See, it wasn't second guess if the first guess is right. It was this choice from the start of the first guess. Let's see if it is correct.The mathematician is in the red house from condition 2 and he is not using Python since he isn't the Hacker.

ch	yellow	blue	red	ivory	green
pr	Developer	Analisyst	Mathematician	h e	h e
cl	Javascript	C#	j cpp	p j cpp	p j cpp
ce	Vim	Atom	Notepad++	b st	b st
ds	Cassandra	Hadoop	r m	r a m	r a m

Condition 4 can be fulfilled. So this means that the man in the fourth house is using Sublime Text

ch	yellow	blue	red	ivory	green
pr	Developer	Analisyst	Mathematician	h e	h e
cl	Javascript	C#	j cpp	p j cpp	p j cpp
ce	Vim	Atom	Notepad++	Sublime Text	Brackets
ds	Cassandra	Hadoop	r m	r a m	r a m

Now let's fulfill condition 13.

ch	yellow	blue	red	ivory	green
pr	Developer	Analisyst	Mathematician	h e	h e
cl	Javascript	C#	j cpp	p j cpp	p j cpp
ce	Vim	Atom	Notepad++	Sublime Text	Brackets
ds	Cassandra	Hadoop	r m	ArangoDB	r m

This means that the Engineer can't live in the fourth house. So the Hacker has to live there and the Engineer has to live in the last house.

ch	yellow	blue	red	ivory	green
pr	Developer	Analisyst	Mathematician	Hacker	Engineer
cl	Javascript	C#	j cpp	p j cpp	p j cpp
ce	Vim	Atom	Notepad++	Sublime Text	Brackets
ds	Cassandra	Hadoop	r m	ArangoDB	r m

The Hacker writes in Python (condition 3) and the Enginner uses MongoDB (condition 14). Now we know that the Mathematician uses Redis.

ch	yellow	blue	red	ivory	green
pr	Developer	Analisyst	Mathematician	Hacker	Engineer
cl	Javascript	C#	j cpp	Python	j cpp
ce	Vim	Atom	Notepad++	Sublime Text	Brackets
ds	Cassandra	Hadoop	Redis	ArangoDB	MongoDB

Now we can use the last condition to deduce that the Mathematician uses Java and the Engineer uses C++

ch	yellow	blue	red	ivory	green
pr	Developer	Analisyst	Mathematician	Hacker	Engineer
cl	Javascript	C#	Java	Python	C++
ce	Vim	Atom	Notepad++	Sublime Text	Brackets
ds	Cassandra	Hadoop	Redis	ArangoDB	MongoDB

Finally! The table is completed! Now we can answer the initial questions. So Vim is used by the Developer and C++ is used by the Engineer.

ch	yellow	blue	red	ivory	green
pr	Developer	Analisyst	Mathematician	Hacker	Engineer
cl	Javascript	C#	Java	Python	C++
ce	Vim	Atom	Notepad++	Sublime Text	Brackets
ds	Cassandra	Hadoop	Redis	ArangoDB	MongoDB