Python List Comprehensions HackerRank Solution
In this article, we will solve the HackerRank List Comprehensions problem in Python.
Task
Let’s learn about list comprehension! You are given three integers x, y, and z representing the dimensions of a cuboid along with an integer n. 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. Please use list comprehensions rather than multiple loops, as a learning exercise.
Example
x = 1
y = 1
z = 2
n = 3
All permutations of [i, j, k] are:
[[0, 0, 0], [0, 0, 1], [0, 0, 2], [0, 1, 0], [0, 1, 1], [0, 1, 2], [1, 0, 0], [1, 0, 1], [1, 0, 2], [1, 1, 0], [1, 1, 1], [1, 1, 2]].
Print an array of the elements that do not sum to n = 3.
[[0, 0, 0], [0, 0, 1], [0, 0, 2], [0, 1, 0], [0, 1, 1], [1, 0, 0], [1, 0, 1], [1, 1, 0], [1, 1, 2]]
Input Format
Four integers x, y, z and n, each on a separate line.
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
Each variable x, y and z will have values of 0 or 1. All permutations of lists in the form [i, j, k] = [[0, 0, 0], [0, 0, 1], [0, 1, 0], [0, 1, 1], [1, 0, 0], [1, 0, 1], [1, 1, 0]].
Remove all arrays that sum to n = 2 to leave only the valid permutations.
Sample Input 1
2
2
2
2
Sample Output 1
[[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: By List Comprehension
if __name__ == '__main__':
x = int(input())
y = int(input())
z = int(input())
n = int(input())
print(list([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))
Steps Used in solving the problem -
Step 1: here x, y, z, and n will take integer type input.
Step 2: then I used a print function to print my list.
Step 3: inside a print function, I have used list Comprehension in which [i,j,k] is my output. After this, I used 3 for loops for the values of i,j & k and after this, I used an if condition.
