List Comprehensions in Python - Hacker Rank Solution
Problem
Tutorial :
Concept :
have already used lists in previous hacks. List comprehensions are an elegant
way to build a list without having to use different for loops to append values
one by one.
These examples
might help. The simplest form of a list comprehension is:
[ expression-involving-loop-variable for loop-variable in sequence ]
This will step over every element in a sequence, successively setting the loop-variable equal to every element one at a time. It will then build up a list by evaluating the expression-involving-loop-variable for each one. This eliminates the need to use lambda forms and generally produces a much more readable code than using map() and a more compact code than using a for loop.
This will step over every element in a sequence, successively setting the loop-variable equal to every element one at a time. It will then build up a list by evaluating the expression-involving-loop-variable for each one. This eliminates the need to use lambda forms and generally produces a much more readable code than using map() and a more compact code than using a for loop.
>> ListOfNumbers = [ x for x in range(10) ] # List of integers from 0 to 9 >> ListOfNumbers [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
List comprehensions can be nested where they take the following form:
[ expression-involving-loop-variables for outer-loop-variable in
outer-sequence for inner-loop-variable in inner-sequence ]
results = [] for outer_loop_variable in outer_sequence: for inner_loop_variable in inner_sequence: results.append( expression_involving_loop_variables )
The final form of list comprehension involves creating a list and filtering it similar to using the filter() method. The filtering form of list comprehension takes the following form:
[ expression-involving-loop-variable for loop-variable in sequence if boolean-expression-involving-loop-variable ]
This form is similar to the simple form of list comprehension, but it evaluates boolean-expression-involving-loop-variable for every item. It also only keeps those members for which the boolean expression is True.
>> ListOfThreeMultiples = [x for x in range(10) if x % 3 == 0] # Multiples of 3 below 10 >> ListOfThreeMultiples [0, 3, 6, 9]
Problem Statement :
Let's
learn about list comprehensions! You are given three integers X,Y and Z representing the dimensions of a cuboid
along with an integer N. You have to print a list of all possible coordinates given by
(i,j,k) on a 3D grid where the sum of i+j+k is not
equal to N. Here, 0<=i<=X; 0<=j<=Y; 0<=k<=Z
Input Format :
Four integers X,Y,Z and N each on four separate lines, respectively.Constraints :
Print the list in lexicographic increasing order.Sample Input 0:
1 1 1 2
Sample Output 0:
[[0, 0, 0], [0, 0, 1], [0, 1, 0], [1, 0, 0], [1, 1, 1]]
Explanation 0 :
Concept
You have already used lists in previous hacks. List comprehensions are an elegant way to build a list without having to use different for loops to append values one by one. This example might help.
Example : You are given two integers x and y . You need to find out the ordered pairs ( i , j ) , such that ( i + j ) is not equal to n and print them in lexicographic order.( 0 <= i <= x ) and ( 0 <= j <= y) This is the code if we dont use list comprehensions in Python.
You have already used lists in previous hacks. List comprehensions are an elegant way to build a list without having to use different for loops to append values one by one. This example might help.
Example : You are given two integers x and y . You need to find out the ordered pairs ( i , j ) , such that ( i + j ) is not equal to n and print them in lexicographic order.( 0 <= i <= x ) and ( 0 <= j <= y) This is the code if we dont use list comprehensions in Python.
python x =
int ( raw_input()) y = int ( raw_input()) n = int ( raw_input()) ar = [] p = 0
for i in range ( x + 1 ) : for j in range( y + 1): if i+j != n: ar.append([])
ar[p] = [ i , j ] p+=1 print arr
Other smaller codes may also exist, but using list comprehensions is always a good option. Code using list comprehensions:
python x = int ( raw_input()) y = int ( raw_input()) n = int ( raw_input()) print [ [ i, j] for i in range( x + 1) for j in range( y + 1) if ( ( i + j ) != n )]
Other smaller codes may also exist, but using list comprehensions is always a good option. Code using list comprehensions:
python x = int ( raw_input()) y = int ( raw_input()) n = int ( raw_input()) print [ [ i, j] for i in range( x + 1) for j in range( y + 1) if ( ( i + j ) != n )]
Sample Input 1 :
2 2 2 2
Sample Output 2 :
[[0, 0, 0], [0, 0, 1], [0, 1, 0], [0, 1, 2], [0, 2, 1], [0, 2, 2], [1, 0, 0], [1, 0, 2], [1, 1, 1], [1, 1, 2], [1, 2, 0], [1, 2, 1], [1, 2, 2], [2, 0, 1], [2, 0, 2], [2, 1, 0], [2, 1, 1], [2, 1, 2], [2, 2, 0], [2, 2, 1], [2, 2, 2]]
Solution :
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | # List Comprehensions in Python - Hacker Rank Solution if __name__ == '__main__': x = int(raw_input()) y = int(raw_input()) z = int(raw_input()) n = int(raw_input()) # List Comprehensions in Python - Hacker Rank Solution START output = []; abc = []; for X in range(x+1): for Y in range(y+1): for Z in range(z+1): if X+Y+Z != n: abc = [X,Y,Z]; output.append(abc); print(output); # List Comprehensions in Python - Hacker Rank Solution END |
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CodeWorld19
Hey, I am Parthe Omkar
[(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]
in lexicographic increasing order
What is the use of n in this.
This isn't using list comprehension
it is told in the question to use list comprehension
so you ur long ans is correct also not correct because it dont follow the question
the answer should be
listComprehensions = [[i,j,k] for i in range(z +1) for j in range(y + 1) for k in range(z + 1) if (i + j + k) != n];
print(listComprehensions)