【codevs1949】兔兔与蛋蛋的游戏

没什么好解释的，博弈论神题，代码都能看懂

var
        m,n,sx,sy,sum:longint;
        map:array[0..40,0..40] of char;
        id:array[0..40,0..40] of longint;
        win,del,v:array[0..2010] of boolean;
        g:array[0..2000,0..2000] of longint;
        link:array[0..2001] of longint;

        procedure get_inf;
        var i,j:longint;
        begin
                readln(n,m);
                for i:=1 to n do
                begin
                        for j:=1 to m do
                        begin
                                read(map[i][j]);
                                if map[i][j]='.' then
                                begin
                                        sx:=i;sy:=j;
                                        sum:=1;id[i][j]:=1;
                                end;
                        end;
                        readln;
                end;
                for i:=1 to n do
                for j:=1 to m do
                if (map[i][j]='X') and ((i+j) and 1=(sx+sy) and 1) or (map[i][j]='O') and ((i+j) and 1 <> (sx+sy) and 1) then
                begin
                        inc(sum);
                        id[i][j]:=sum;
                end;
                for i:=1 to n do
                for j:=1 to m do
                if id[i][j]>0 then
                begin
                        if id[i-1][j]>0 then
                        begin
                                inc(g[id[i][j],0]);
                                g[id[i][j],g[id[i][j],0]]:=id[i-1][j];
                                inc(g[id[i-1][j],0]);
                                g[id[i-1][j],g[id[i-1][j],0]]:=id[i][j];
                        end;
                        if id[i][j-1]>0 then
                        begin
                                inc(g[id[i,j],0]); g[id[i,j],g[id[i,j],0]]:=id[i,j-1];
                                inc(g[id[i,j-1],0]); g[id[i,j-1],g[id[i,j-1],0]]:=id[i,j];
                        end;
                end;
        end;

        function find(x:longint):boolean;
        var i,y:longint;
        begin
                v[x]:=true;
                for y:=1 to g[x][0] do
                begin
                        i:=g[x][y];
                        if not v[i] and not del[i] then
                        begin
                                v[i]:=true;
                                if (link[i]=0) or find(link[i]) then
                                begin
                                        link[i]:=x;link[x]:=i;
                                        exit(true);
                                end;
                        end;
                end;
                exit(false);
        end;

        function check:boolean;
        var t:longint; can:boolean;
        begin
                if link[id[sx,sy]]=0 then exit(false);
                del[id[sx,sy]]:=true; t:=link[id[sx,sy]];
                link[t]:=0; link[id[sx,sy]]:=0;
                fillchar(v,sizeof(v),0);
                can:=find(t);
                if not can then
                begin
                link[t]:=id[sx,sy];
                link[id[sx,sy]]:=t;
                end;
                del[id[sx,sy]]:=false;
                exit(not can);
        end;

        procedure main;
        var
                i,q,tot,x,y,t:longint;
        begin
                for i:=1 to sum do
                if link[i]=0 then
                begin
                        fillchar(v,sizeof(v),0);
                        find(i);
                end;
                read(q); tot:=0;
                for i:=1 to q do
                begin
                        win[i]:=check;
                        read(x,y);
                        del[id[sx,sy]]:=true;
                        t:=link[id[sx,sy]];
                        link[t]:=0; link[id[sx,sy]]:=0;
                        fillchar(v,sizeof(v),0);
                        find(t);
                        sx:=x; sy:=y;
                        if win[i] and check then inc(tot) else win[i]:=false;
                        read(x,y);
                        del[id[sx,sy]]:=true;
                        t:=link[id[sx,sy]];
                        link[t]:=0; link[id[sx,sy]]:=0;
                        fillchar(v,sizeof(v),0);
                        find(t);
                        sx:=x; sy:=y;
                end;
                writeln(tot);
                for i:=1 to q do
                if win[i] then writeln(i);
        end;


        begin
                get_inf;
                main;
        end.