var a:array[0..maxn,0..maxn]of boolean;

f:array[0..maxn,0..maxn]of longint;

ans,i,j,k,m,n,ii,jj,si,sj:longint;

flog:boolean;

begin

readln(m,n);

for i:=1 to m do

for j:=1 to n do

begin

read(k);

if k=1 then

begin

a[i,j]:=true;

f[i,j]:=1;

end

else

begin

a[i,j]:=false;

f[i,j]:=0;

end;

end;

for i:=2 to m do

for j:=2 to n do

begin

if not a[i,j] then continue;

if not a[i-1,j-1] then continue;

flog:=false;

k:=f[i-1,j-1];

si:=f[i-1,j];

// for ii:=i downto i-k do

// if a[ii,j] then inc(si);

sj:=f[i,j-1];

// for jj:=j downto j-k do

// if a[i,jj] then inc(sj);

if si>sj then f[i,j]:=sj else f[i,j]:=si;

if f[i,j]>k then f[i,j]:=k;

inc(f[i,j]);

// if f[i,j]=4 then writeln(i,j,'!');

end;

ans:=0;

for i:=1 to m do

for j:=1 to n do

if f[i,j]>ans then ans:=f[i,j];

writeln(ans*ans);

end.

连调试代码一同贴上来 大家应该就能看懂我的思路了。