Answer to Question #166820 in Python for prathyusha

Question

Anti-Diagonals

Given a MxN matrix,write a program to print all Anti-Diagonals elements of matrix

Input

The first line of input will contain a M, N values separated by space.

The second line will contain matrix A of dimensions MxN.

Output

The output should contain anti-diagonal elements separated by a line.

Explanation

For example, if M = 4, N = 4

Matrix A:

4 4

1 2 3 4

5 6 7 8

9 10 11 12

13 14 15 16

So the output should be

1

2 5

3 6 9

4 7 10 13

8 11 14

12 15

16

Sample Input 1

2 3

1 5 5

2 7 8

Sample Output 1

1

5 2

5 7

8

Sample Input 2

3 4

1 2 3 4

5 6 7 8

9 10 11 12

Sample Output 2

1

2 5

3 6 9

4 7 10

8 11

12

Answer 1

def antidiagonals(M, N, matrix):
    """Prints antidiagonals one per line of MxN matrix represented
        by 1-dimantional array

    >>> antidiagonals(2, 3, [1, 5, 5, 2, 7, 8])
    1
    5 2
    5 7
    8
    >>> antidiagonals(3, 4, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12])
    1
    2 5
    3 6 9
    4 7 10
    8 11
    12
    """
    antidiagonals = [[] for _ in range(M+N-1)]
    for i in range(M*N):
        adindex = (i // N) + (i % N)
        antidiagonals[adindex].append(matrix[i])
    for d in antidiagonals:
        print(*d)

# Driver code
M, N = list(map(int, input('M N: ').split()))
A = []
for i in range(1, M+1):
    A += map(int, input('A[%d]: ' % i).split())

antidiagonals(M, N, A)

if __name__ == '__main__':
  import doctest
  doctest.testmod(verbose=True)