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x, y, z, n = int(input()), int(input()), int(input()), int(input())
print ([[a,b,c] for a in range(0,x+1) for b in range(0,y+1) for c in range(0,z+1) if a + b + c != n ])
Looks good, but to avoid those repetitive input calls you could do something like:
x, y, z, n = (int(input()) for _ in range(4))
Thanks for the input. Will use this from now! :D
Great tip! BTW is there any reason for using '_' as the dummy variable? What's wrong with using letter, for example 'i'?
_ is used to signify that even though something is being returned, we don't plan to use that variable any where.
gives the following error in above code in python 2.7.13 : at 0x7f60c947e910>
It's also an old Perl trick. If you just performed the input command without assigning the data to anything, it was still available in the $_ variable by default.
just a small suggestion ..the 4 in for loop will be n+1
N is the number to compare the sum of x, y, z. The loop should actually have 4, as mentioned, for the inputs : x,y,z & n.
in py2 can be w/o int()
x,y,z,n = [input() for i in range(4)]
print [[a,b,c] for a in range(x+1) for b in range(y+1) for c in range(z+1) if a+b+c != n]
Doesn't work on python3.5
int is not required for input()
Yes it is in Python 3
I'm using this one line, but my compiler reads "wrong answer". Am I missing something? What else do I need to write?
Disregard, I figured it out.
I am a newbie to python and its not clear to me. WHY 4? And how the variable iterate from 0 to 1.
range(4) means range(0,4) that is 0,1,2,3 which is because we ahve to read 4 inputs
Read list comprehensions for more. It is an easy way to build a list.
How is this syntax even valid. Just wondering.
what does for _ in range(4) do ? what's the significance of the underscore? @omalsa04
But instead of range[0,x] you could do
print ([[a,b,c] for a in range(x+1) for b in range(y+1) for c in range(z+1) if a + b + c != n ])
Trade three +1's for a +1 and a -1 at the right place :P
x, y, z, n = (int(raw_input())+1 for _ in range(4))
print [[a,b,c] for a in range(x) for b in range(y) for c in range(z) if a+b+c!=n-1]
although this method is more simple, but it not easy to understand.
I liked this method compared to other's.
really like this solution. simple and easy to read
Hey, I have heard that int(raw_input()) is faster.
raw_input() was renamed to input() in python 3
Can you tell me how python carries out list comprehension internally? How come this generates lists in lexicographic increasing order (i.e z increases first, then y, then x)?
It is in lexographical order due to the nature of the loops.
Spaced out it looks somewhat like
for a in range(x+1):
for b in range(y+1):
for c in range(z+1):
if a + b + c != n:
print(stuff is here)
We start at [0,0,0].
Then c will increment to get to [0,0,1]
When c hits [0,0,z], we get [0,1,0] as the next in the loop. This pattern continues and gives us the lexographical ordering required of the output.
it's very helpfull to understanding that what is actualy asking
Thank you. This is the a verbose response, but clearly the most elegant to understand what's going on.
yup! i understand.
Thanks for your solution, now we understand how it's word.
This solution is good! Utilising list comprehension to a good extreme.
Not reqired to put input() for each variable .just call the input for _ in range(no of variables);
a , b = int (input()) for _ in range ( 2 ):
Thanks for sharing your elegant code.
I'm a newbie to Python, its great to see such beautiful code :)
I don't like these "direct print" solutions. In my opinion the problem stated to create a list then print it, not just print something in a list. In other words in your solutions the list itself doesn't exist, can not be used later, it just collected when printed out. What do you think?
OK, I found the answer! I can put list = instead of printoing out, then print the list. It wasn't clear for me three for loops output is collected in a list, so no need for any append tricks!
Nice answer. As an alternative, to avoid multiple for loops you can use product:
combinations = list(product(range(x+1), range(y+1), range(z+1)))
print([list(a) for a in combinations if sum(a) != n])
it is not solution, as question was to form list comperhention. You just put out data to screen in right format, no list comperhetion created
Could someone explain to me what, exactly, this code does (like, statement-by-statement)(other than the input part I understand that I mostly mean the list comprehension)? I sort of have a basic understanding of how it works, but having some trouble wrapping my head around list comprehensions and how exactly the work. Mostly the "for a in range(0,x+1)" parts. What exactly does that do? Why is it (0,x+1)? Thanks in advance.
Just search for something like 'python range' and you will get pages like this.
just for curiosity, why you are using range(0,x+1) in the print function?
why do you need two square brackets? Can someone explain this to me?
The problem states that it wants the output list printed in 'increasing order'. It should be more clear what this means. I initially interpreted this to mean that [1,1,0] would come before [3,0,0] because 1+1+0=2 is less than 3+0+0=3. But this is not the order that the comprehension list method would generate the list. And would likely involve some method of sorting a 3D array that many new users would not know at this point, so I'm assuming this is not what is meant. This problem is not clarified with the chosen example values of x=1, y=1, z=1, and N=2.
The problem could be addressed by just using larger example values, allowing us to infer from the example output which interpretation of 'increasing order' is intended.
What does N represent? Why should X+Y+Z not equal N? And what do the subscript i's represent? I don't understand the question.
@scintilla read the question properly. 0<=Xi<=X same for Yi and Zi.N is specified in the question.
I am sooooooooooooo confused with the question holy cow.
You can't just say "Read the question properly". He said he doesn't understand the syntax of the question.
This is a type of mathematic short-hand that not all of us understand. I for one don't even know what this short-hand is called or I'd look it up myself.
Try now, I have updated the statement :)
Thank you for the follow-up shashank21j, your revision to the statement has been helpful, but I still have some questions about the way the question is worded and why.
1.Why must i+j+k not be equal to N and does this mean it can be greater than N?
2.Please define "lexicographic increasing order"
I for one agree that list comprehension in python is a fairly simple subject, the crux of this problem for me however, is bridging the communication gap/understanding the essance of the problem you're asking.
Many people who use your site are self taught in coding and do not have a formal discrete mathematics background.
i + j + k != N is just an added condition in this problem so you can use 1 if statement inside your list compehension syntax. It can be greater than N as long as i, j and k are in their respective limits.
Thanks again shashank21j! :)
Shouldn't the statement include that X,Y,Z are integers that are possible maximums? It is a fairly important point no? For example dimensions of 2,2,2 given the statement as it currently is, means there is only 1 possible cube with 8 coordinates.
Where as if we said that 2 is the max integer value for X,Z,Y , we can have more than 1 possible cuboid. For example a 1,1,2 cuboid.
I have also difficulty understanding the question.
Can anybody make me understand this question ? I went through few comments what this question all about but still I'm not clear
You're given 4 numbers. The first 3 correspond to the maximum dimensions of a cube. y is the maximum height, x is the maximum width, and z is the maximum depth.
You're supposed to calulate every possible set of dimensions [x,y,z], under the condition that none exceed the input values, and that x+y+z does not add up to n.
thanks that was very helpful!
Thanks for the explanation eric. I've just one more question that in this lexicographic order the last dimension is [1,1,1], but our N is given to be 2. Thus the sum of x+y+z becomes 3 which is greater than N. How is this condition satisfied?? Pls explain.
The only restriction relating to N is that i + j + k != N. i+j+k>N is perfectly valid.
Thanks for your help. Was helpful and appreciate that
Helpful explanation! Thank you
I agree that what you say is the intention of the challenge, But my problem with this challenge is that it never states that X,Y,Z are maximums.
Sample input of 2,2,2 can only be 1 cube with 8 dimensions.
I feel like the statement should be change to express what you are saying, that X,Y,Z correspond to maximum integer dimensions.
print([[i,j,k] for i in range(x+1) for j in range(y+1) for k in range(z+1) if sum([i,j,k]) != n])
I feel like I am missing the point of this exercise with my solution. Can someone please comment on how to make my code more pythonesque and utilize list comprehensions better.
X = int(raw_input())
Y = int(raw_input())
Z = int(raw_input())
N = int(raw_input())
Xi = [x for x in range(X+1)]
Yi = [y for y in range(Y+1)]
Zi = [z for z in range(Z+1)]
results = 
for x in Xi:
for y in Yi:
for z in Zi:
if x + y + z != N:
this is fine.
Xi Yi and Zi are not much of use here. You can make your code smaller
cuboid = 
results = [cuboid.append([x, y, z]) for x in range(X+1) for y in range(Y+1) for z in range(Z+1) if x + y + z != N]
Less lines, more Pythonic
That's really great :)
print ([[a,b,c] for a in range(int(input())+1) for b in range(int(input())+1) for c in range(int(input())+1) if a+b+c!=int(input())])
why does this code not work?
can you explain?
The inputs should be captured before the for loop is executed. In this case, a new input is expected for every iteration of the for loop. Try capturing the inputs first inside some variables and use those variables here. That will work.
You don't even need to have the cuboid list to be honest :)
print ([[a,b,c] for a in range(0,x+1) for b in range(0,y+1) for c in range(0,z+1) if a + b + c != n ])
ha!, I realized that a day later. Thanks for clearing it up though gkeswani92
listCoords = [[x1, y1, z1] for x1 in range(x+1) for y1 in range(y+1) for z1 in range(z+1) if x1+y1+z1!=n]
x = int(raw_input())
y = int(raw_input())
z = int(raw_input())
n = int(raw_input())
print([ [i, j, k] for i, j, k in itertools.product(range(x+1), range(y+1), range(z+1)) if i+j+k != n ])
Prompts made it easy to solve.
Here's my code:
print([[i,j,k] for i in range(x+1) for j in range(y+1) for k in range(z+1) if i+j+k !=n])
Instead of using nested comprehensions, I used itertools to create the cartesian product:
l = [[i,j,k] for (i,j,k) in itertools.product(range(x+1), range(y+1),range(z+1)) if i+j+k!=n]