#### Spiral Print

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```"""
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:
# must be
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

# horizotal printing increasing
for i in range(0, mat_col):
print(a[0][i])
# vertical printing down
for i in range(1, mat_row):
print(a[i][mat_col - 1])
# horizotal printing decreasing
if mat_row > 1:
for i in range(mat_col - 2, -1, -1):
print(a[mat_row - 1][i])
# vertical printing up
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

# Other Easy to understand Approach

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 []

# driver code
if __name__ == "__main__":
import doctest

doctest.testmod()

a = [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]]
spiral_print_clockwise(a)
```