Leetcode 562 Solution

This article provides solution to leetcode question 562 (longest-line-of-consecutive-one-in-matrix)
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https://leetcode.com/problems/longest-line-of-consecutive-one-in-matrix

Solution

class Solution:
    def longestLine(self, mat: List[List[int]]) -> int:
        m = len(mat)
        n = len(mat[0])

        dp = [[[0, 0, 0, 0] for _ in range(n)] for _ in range(m)]

        ans = 0
        for i in range(m):
            for j in range(n):
                if mat[i][j] == 1:
                    dp[i][j][0] = 1 + (dp[i][j - 1][0] if j > 0 else 0)
                    dp[i][j][1] = 1 + (dp[i - 1][j][1] if i > 0 else 0)
                    dp[i][j][2] = 1 + (dp[i - 1][j - 1][2] if i > 0 and j > 0 else 0)
                    dp[i][j][3] = 1 + (dp[i - 1][j + 1][3] if i > 0 and j + 1 < n else 0)
                else:
                    dp[i][j][0] = 0
                    dp[i][j][1] = 0
                    dp[i][j][2] = 0
                    dp[i][j][3] = 0
                ans = max(ans, max(dp[i][j]))
        return ans