HTMLify

class Solution:
    def maxSideLength(self, mat: List[List[int]], threshold: int) -> int:
        m, n = len(mat), len(mat[0])
        pref = [[0] * (n + 1) for _ in range(m + 1)]
        
        for r in range(1, m + 1):
            for c in range(1, n + 1):
                pref[r][c] = mat[r-1][c-1] + pref[r-1][c] + pref[r][c-1] - pref[r-1][c-1]
        
        res = 0
        for r in range(1, m + 1):
            for c in range(1, n + 1):
                while r + res <= m and c + res <= n:
                    if pref[r+res][c+res] - pref[r-1][c+res] - pref[r+res][c-1] + pref[r-1][c-1] <= threshold:
                        res += 1
                    else:
                        break
        return res