Skip to content

Commit 06f0a43

Browse files
darrylbalderasdarrylbalderas
authored
Merge pull request #35 from miguelHx/miguel_1.8_zero_matrix
Miguel 1.8 - Zero Matrix [Python]
2 parents d6b27d8 + a080c5a commit 06f0a43

File tree

1 file changed

+189
-0
lines changed

1 file changed

+189
-0
lines changed

‎Python/chapter01/1.8 - Zero Matrix/miguel_1.8_sol.py

Lines changed: 189 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,189 @@
1+
"""
2+
Python version 3.7.0
3+
1.8 - Zero Matrix
4+
Write an algorithm such that if an element in an MxN matrix is 0,
5+
its entire row and column are set to 0
6+
"""
7+
import unittest
8+
from typing import List
9+
10+
11+
def zero_matrix(matrix: List[List[int]]) -> List[List[int]]:
12+
"""
13+
zero_matrix will take in an MxN matrix and when a 0 element is found,
14+
the whole column and row will be set to 0.
15+
The algorithm works by first scanning for
16+
rows and columns where there is a 0 and store into a set.
17+
Then we go through each stored row and column indices
18+
and proceed to set the rows and columns to 0.
19+
Runtime: O(M * N)
20+
Space Complexity: O(M + N)
21+
:param matrix: an MxN matrix. M is the number of rows, N is the number of columns
22+
:return: a zero-modified matrix
23+
"""
24+
M = len(matrix)
25+
N = len(matrix[0])
26+
27+
rows_to_zero = set()
28+
cols_to_zero = set()
29+
# first, scan for coordinates of 0s
30+
for i, row in enumerate(matrix):
31+
for j, num in enumerate(row):
32+
if num != 0:
33+
continue
34+
# otherwise, save row or col to rows or cols to zero set
35+
rows_to_zero.add(i)
36+
cols_to_zero.add(j)
37+
for i in rows_to_zero:
38+
# set row to 0 by looping through columns of current row
39+
for k in range(N):
40+
matrix[i][k] = 0
41+
42+
for j in cols_to_zero:
43+
# set column to 0 by looping through rows of current column
44+
for l in range(M):
45+
matrix[l][j] = 0
46+
return matrix
47+
48+
49+
class TestZeroMatrixFunction(unittest.TestCase):
50+
51+
def setUp(self):
52+
self.cases = [
53+
(
54+
[
55+
[1, 2, 3, 4],
56+
[5, 6, 0, 8],
57+
[9, 10, 11, 12],
58+
[13, 14, 15, 16]
59+
],
60+
[
61+
[1, 2, 0, 4],
62+
[0, 0, 0, 0],
63+
[9, 10, 0, 12],
64+
[13, 14, 0, 16]
65+
]
66+
),
67+
(
68+
[
69+
[1, 2],
70+
[3, 4],
71+
[5, 6],
72+
[7, 8],
73+
[9, 0]
74+
],
75+
[
76+
[1, 0],
77+
[3, 0],
78+
[5, 0],
79+
[7, 0],
80+
[0, 0]
81+
],
82+
),
83+
(
84+
[
85+
[1, 2],
86+
[0, 4],
87+
[5, 6],
88+
[7, 8],
89+
[9, 0]
90+
],
91+
[
92+
[0, 0],
93+
[0, 0],
94+
[0, 0],
95+
[0, 0],
96+
[0, 0]
97+
]
98+
),
99+
(
100+
[
101+
[1, 2, 3, 4, 5, 6, 0, 8, 9],
102+
[9, 8, 7, 6, 5, 4, 3, 2, 1],
103+
],
104+
[
105+
[0, 0, 0, 0, 0, 0, 0, 0, 0],
106+
[9, 8, 7, 6, 5, 4, 0, 2, 1],
107+
]
108+
),
109+
(
110+
[
111+
[0]
112+
],
113+
[
114+
[0]
115+
]
116+
),
117+
(
118+
[
119+
[1]
120+
],
121+
[
122+
[1]
123+
]
124+
),
125+
(
126+
[
127+
[1, 2],
128+
[3, 4]
129+
],
130+
[
131+
[1, 2],
132+
[3, 4]
133+
]
134+
),
135+
(
136+
[
137+
[0, 1, 2],
138+
[0, 3, 4],
139+
[0, 5, 6],
140+
[0, 7, 8]
141+
],
142+
[
143+
[0, 0, 0],
144+
[0, 0, 0],
145+
[0, 0, 0],
146+
[0, 0, 0]
147+
]
148+
),
149+
(
150+
[
151+
[1, 2, 3, 4],
152+
[5, 6, 0, 8],
153+
[9, 10, 0, 12],
154+
[13, 14, 15, 16]
155+
],
156+
[
157+
[1, 2, 0, 4],
158+
[0, 0, 0, 0],
159+
[0, 0, 0, 0],
160+
[13, 14, 0, 16]
161+
]
162+
),
163+
(
164+
[
165+
[0, 0, 0, 0],
166+
[1, 2, 3, 4],
167+
[5, 6, 7, 8],
168+
[9, 10, 11, 12]
169+
],
170+
[
171+
[0, 0, 0, 0],
172+
[0, 0, 0, 0],
173+
[0, 0, 0, 0],
174+
[0, 0, 0, 0]
175+
]
176+
),
177+
(
178+
[[0] * 1000 for _ in range(1000)],
179+
[[0] * 1000 for _ in range(1000)],
180+
)
181+
]
182+
183+
def test_zero_matrix(self):
184+
for matrix, expected in self.cases:
185+
self.assertEqual(zero_matrix(matrix), expected, msg=(matrix, expected))
186+
187+
188+
if __name__ == '__main__':
189+
unittest.main()

0 commit comments

Comments
 (0)