Problem $4$

Given an $n**n$ binary matrix $M($each entry of the matrix is $0$ or $1),$ find the largest square

containing only $0$ s and return it$.($That is$,$ return $(i,j,k)$ where

AAi$xi+k,$AAj$yj+k,M[x,y]=0$

and $k$ is maximum.$)$ Your algorithm should work in $O(n^2).$