• Time:O(mn)
• Space:O(mn)

## C++

``````class Solution {
public:
int longestLine(vector<vector<int>>& mat) {
const int m = mat.size();
const int n = mat[0].size();
int ans = 0;
// dp[i][j][0] := horizontal
// dp[i][j][1] := vertical
// dp[i][j][2] := diagonal
// dp[i][j][3] := anti-diagonal
vector<vector<vector<int>>> dp(m, vector<vector<int>>(n, vector<int>(4)));

for (int i = 0; i < m; ++i)
for (int j = 0; j < n; ++j)
if (mat[i][j] == 1) {
dp[i][j][0] = j > 0 ? dp[i][j - 1][0] + 1 : 1;
dp[i][j][1] = i > 0 ? dp[i - 1][j][1] + 1 : 1;
dp[i][j][2] = (i > 0 && j > 0) ? dp[i - 1][j - 1][2] + 1 : 1;
dp[i][j][3] = (i > 0 && j < n - 1) ? dp[i - 1][j + 1][3] + 1 : 1;
ans = max(ans, *max_element(begin(dp[i][j]), end(dp[i][j])));
}

return ans;
}
};
``````

## JAVA

``````class Solution {
public int longestLine(int[][] mat) {
final int m = mat.length;
final int n = mat[0].length;
int ans = 0;
// dp[i][j][0] := horizontal
// dp[i][j][1] := vertical
// dp[i][j][2] := diagonal
// dp[i][j][3] := anti-diagonal
int[][][] dp = new int[m][n][4];

for (int i = 0; i < m; ++i)
for (int j = 0; j < n; ++j)
if (mat[i][j] == 1) {
dp[i][j][0] = j > 0 ? dp[i][j - 1][0] + 1 : 1;
dp[i][j][1] = i > 0 ? dp[i - 1][j][1] + 1 : 1;
dp[i][j][2] = (i > 0 && j > 0) ? dp[i - 1][j - 1][2] + 1 : 1;
dp[i][j][3] = (i > 0 && j < n - 1) ? dp[i - 1][j + 1][3] + 1 : 1;
for (int k = 0; k < 4; ++k)
ans = Math.max(ans, dp[i][j][k]);
}

return ans;
}
}
``````

## Python

``````class Solution:
def longestLine(self, mat: List[List[int]]) -> int:
m = len(mat)
n = len(mat[0])
ans = 0
# dp[i][j][0] := horizontal
# dp[i][j][1] := vertical
# dp[i][j][2] := diagonal
# dp[i][j][3] := anti-diagonal
dp = [[[0] * 4 for j in range(n)] for _ in range(m)]

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

return ans
``````