MediumNo. 0562LeetCode Premium
Longest Line of Consecutive One in Matrix — LeetCode 562 Python Solution
- Pattern
- Matrix and Grid
- Topics
- Array, Dynamic Programming, Matrix
- Reading time
- 3 min
- Source
- leetcode.com
The problem
Given an m x n binary matrix mat, return the length of the longest line of consecutive one in the matrix. The line could be horizontal, vertical, diagonal, or anti-diagonal.
Example
- Input
- mat = [[0,1,1,0],[0,1,1,0],[0,0,0,1]]
- Output
- 3
Python solution
class Solution:
def longestLine(self, mat: List[List[int]]) -> int:
m, n = len(mat), len(mat[0])
a = [[0] * (n + 2) for _ in range(m + 2)]
b = [[0] * (n + 2) for _ in range(m + 2)]
c = [[0] * (n + 2) for _ in range(m + 2)]
d = [[0] * (n + 2) for _ in range(m + 2)]
ans = 0
for i in range(1, m + 1):
for j in range(1, n + 1):
if mat[i - 1][j - 1]:
a[i][j] = a[i - 1][j] + 1
b[i][j] = b[i][j - 1] + 1
c[i][j] = c[i - 1][j - 1] + 1
d[i][j] = d[i - 1][j + 1] + 1
ans = max(ans, a[i][j], b[i][j], c[i][j], d[i][j])
return ansComplexity
- Time
- O(m × n)
- Space · auxiliary
- O(m × n)where m and n are the number of rows and columns in the matrix, respectively
Pattern: Matrix and Grid
Treat a 2-D grid as a graph whose neighbours are the four adjacent cells. LeetCode 562. Longest Line of Consecutive One in Matrix is filed here because LeetCode tags it Matrix, which is the vocabulary this hub collects.
The matrix and grid guide has the Python template for the pattern and the 216 LeetCode problems that use it.
Related problems
| No. | Problem | Difficulty |
|---|---|---|
| 0063 | Unique Paths II | Medium |
| 0064 | Minimum Path Sum | Medium |
| 0085 | Maximal Rectangle | Hard |
| 0174 | Dungeon Game | Hard |
| 0221 | Maximal Square | Medium |
| 0329 | Longest Increasing Path in a Matrix | Hard |
Frequently asked questions
- How hard is LeetCode 562. Longest Line of Consecutive One in Matrix?
LeetCode 562. Longest Line of Consecutive One in Matrix is rated Medium on LeetCode.
- What is the time complexity of LeetCode 562. Longest Line of Consecutive One in Matrix?
The Python solution on this page runs in O(m × n).
- What is the space complexity of LeetCode 562. Longest Line of Consecutive One in Matrix?
The Python solution on this page uses O(m × n), where m and n are the number of rows and columns in the matrix, respectively auxiliary space.
- What topics does LeetCode 562. Longest Line of Consecutive One in Matrix cover?
LeetCode 562. Longest Line of Consecutive One in Matrix is tagged Array, Dynamic Programming and Matrix on LeetCode.
- Is LeetCode 562. Longest Line of Consecutive One in Matrix a premium problem?
Yes. LeetCode 562. Longest Line of Consecutive One in Matrix is a LeetCode Premium problem, so the full statement and test cases require a paid LeetCode subscription.