"""
This program print the matrix in spiral form.
This problem has been solved through recursive way.
Matrix must satisfy below conditions
i) matrix should be only one or two dimensional
ii) number of column of all rows should be equal
"""
def check_matrix(matrix: list[list[int]]) -> bool:
matrix = [list(row) for row in matrix]
if matrix and isinstance(matrix, list):
if isinstance(matrix[0], list):
prev_len = 0
for row in matrix:
if prev_len == 0:
prev_len = len(row)
result = True
else:
result = prev_len == len(row)
else:
result = True
else:
result = False
return result
def spiral_print_clockwise(a: list[list[int]]) -> None:
"""
>>> spiral_print_clockwise([[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]])
1
2
3
4
8
12
11
10
9
5
6
7
"""
if check_matrix(a) and len(a) > 0:
a = [list(row) for row in a]
mat_row = len(a)
if isinstance(a[0], list):
mat_col = len(a[0])
else:
for dat in a:
print(dat)
return
for i in range(mat_col):
print(a[0][i])
for i in range(1, mat_row):
print(a[i][mat_col - 1])
if mat_row > 1:
for i in range(mat_col - 2, -1, -1):
print(a[mat_row - 1][i])
for i in range(mat_row - 2, 0, -1):
print(a[i][0])
remain_mat = [row[1 : mat_col - 1] for row in a[1 : mat_row - 1]]
if len(remain_mat) > 0:
spiral_print_clockwise(remain_mat)
else:
return
else:
print("Not a valid matrix")
return
def spiral_traversal(matrix: list[list]) -> list[int]:
"""
>>> spiral_traversal([[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]])
[1, 2, 3, 4, 8, 12, 11, 10, 9, 5, 6, 7]
Example:
matrix = [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]]
Algorithm:
Step 1. first pop the 0 index list. (which is [1,2,3,4] and concatenate the
output of [step 2])
Step 2. Now perform matrix’s Transpose operation (Change rows to column
and vice versa) and reverse the resultant matrix.
Step 3. Pass the output of [2nd step], to same recursive function till
base case hits.
Dry Run:
Stage 1.
[1, 2, 3, 4] + spiral_traversal([
[8, 12], [7, 11], [6, 10], [5, 9]]
])
Stage 2.
[1, 2, 3, 4, 8, 12] + spiral_traversal([
[11, 10, 9], [7, 6, 5]
])
Stage 3.
[1, 2, 3, 4, 8, 12, 11, 10, 9] + spiral_traversal([
[5], [6], [7]
])
Stage 4.
[1, 2, 3, 4, 8, 12, 11, 10, 9, 5] + spiral_traversal([
[5], [6], [7]
])
Stage 5.
[1, 2, 3, 4, 8, 12, 11, 10, 9, 5] + spiral_traversal([[6, 7]])
Stage 6.
[1, 2, 3, 4, 8, 12, 11, 10, 9, 5, 6, 7] + spiral_traversal([])
"""
if matrix:
return list(matrix.pop(0)) + spiral_traversal(list(zip(*matrix))[::-1])
else:
return []
if __name__ == "__main__":
import doctest
doctest.testmod()
a = [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]]
spiral_print_clockwise(a)