1878. Get Biggest Three Rhombus Sums in a Grid

from sortedcontainers import SortedSet


class Solution:
    def getBiggestThree(self, grid: List[List[int]]) -> List[int]:
        m, n = len(grid), len(grid[0])
        s1 = [[0] * (n + 2) for _ in range(m + 1)]
        s2 = [[0] * (n + 2) for _ in range(m + 1)]
        for i, row in enumerate(grid, 1):
            for j, x in enumerate(row, 1):
                s1[i][j] = s1[i - 1][j - 1] + x
                s2[i][j] = s2[i - 1][j + 1] + x
        ss = SortedSet()
        for i, row in enumerate(grid, 1):
            for j, x in enumerate(row, 1):
                l = min(i - 1, m - i, j - 1, n - j)
                ss.add(x)
                for k in range(1, l + 1):
                    a = s1[i + k][j] - s1[i][j - k]
                    b = s1[i][j + k] - s1[i - k][j]
                    c = s2[i][j - k] - s2[i - k][j]
                    d = s2[i + k][j] - s2[i][j + k]
                    ss.add(
                        a + b + c + d - grid[i + k - 1][j - 1] + grid[i - k - 1][j - 1]
                    )
                while len(ss) > 3:
                    ss.remove(ss[0])
        return list(ss)[::-1]