bzoj1923[Sdoi2010]外星千足虫（高斯消元）

 1 program rrr(input,output);
 2 var
 3   a:array[0..2020,0..1010]of boolean;
 4   n,m,i,j,k,ans:longint;
 5   c:char;
 6   flag,t:boolean;
 7 begin
 8    assign(input,‘r.in‘);assign(output,‘r.out‘);reset(input);rewrite(output);
 9    readln(n,m);
10    for i:=1 to m do
11       begin
12          for j:=1 to n do begin read(c);if c=‘0‘ then a[i,j]:=false else a[i,j]:=true; end;
13          read(c);read(c);if c=‘0‘ then a[i,n+1]:=false else a[i,n+1]:=true;
14          readln;
15       end;
16    ans:=0;flag:=true;
17    for i:=1 to n do
18       begin
19          for k:=i to m do if a[k,i] then break;
20          if not a[k,i] then begin flag:=false;break; end;
21          if k>ans then ans:=k;
22          for j:=i to n+1 do begin t:=a[i,j];a[i,j]:=a[k,j];a[k,j]:=t; end;
23          for j:=1 to m do
24             if (j<>i) and a[j,i] then
25                for k:=i to n+1 do a[j,k]:=a[j,k] xor a[i,k];
26        end;
27    if flag then begin writeln(ans);for i:=1 to n do if a[i,n+1] then writeln(‘?y7M#‘) else writeln(‘Earth‘); end else write(‘Cannot Determine‘);
28    close(input);close(output);
29 end.