BZOJ1443 游戏game （二分图染色+匈牙利算法）

先对整幅图进行二分图染色，再跑一遍匈牙利算法。如果最大匹配数=点数*2，那么输出WIN。

对于任何一个非必须在最大匹配上的点，即为所求的点。

 Program Test375num2;
 type arr=record
         u,v,next:longint;
         end;
 const dx:array[..] of longint=(,,-,);
       dy:array[..] of longint=(,-,,);
       maxn=;
       maxm=maxn*;
 var map:array[..,..] of longint;
     cl:array[..maxn] of longint;
     eg:array[..maxm] of arr;
     last:array[..maxn] of longint;
     l,r,f:array[..maxn] of longint;
     pd:array[..maxn] of boolean;
     i,j,m,n,num,sum,x:longint;
     ch:char;
 procedure dfs(i,j,w:longint);
 var k,x,y:longint;
 begin
     cl[map[i,j]]:=w;
     for k:= to  do
     begin
         x:=i+dx[k]; y:=j+dy[k];
         if (map[x,y]>) and (cl[map[x,y]]=) then
             dfs(x,y,-w);
     end;
 end;
 procedure add(u,v:longint);
 begin
     inc(sum);
     eg[sum].u:=u;
     eg[sum].v:=v;
     eg[sum].next:=last[u];
     last[u]:=sum;
 end;
 procedure put(i,j:longint);
 var k,x,y:longint;
 begin
     for k:= to  do
     begin
         x:=i+dx[k]; y:=j+dy[k];
         if (map[x,y]>) then add(map[i,j],map[x,y]);
     end;
 end;
 function Hungarian(u:longint):boolean;
 var i,v:longint;
 begin
     i:=last[u];
     while i<> do
     begin
         v:=eg[i].v;
         if not pd[v] then
         begin
             pd[v]:=true;
             if (l[v]=) or Hungarian(l[v]) then
             begin
                 r[u]:=v;
                 l[v]:=u;
                 exit(true);
             end;
         end;
         i:=eg[i].next;
     end;
     exit(false);
 end;
 procedure dfsl(u:longint);
 var i,v:longint;
 begin
     f[u]:=;
     i:=last[u];
     while i<> do
     begin
         v:=eg[i].v;
         if f[v]= then
         begin
             f[v]:=;
             if f[l[v]]= then dfsl(l[v]);
         end;
         i:=eg[i].next;
     end;
 end;

 procedure dfsr(u:longint);
 var i,v:longint;
 begin
     f[u]:=;
     i:=last[u];
     while i<> do
     begin
         v:=eg[i].v;
         if f[v]= then
         begin
             f[v]:=;
             if f[r[v]]= then dfsr(r[v]);
         end;
         i:=eg[i].next;
     end;
 end;
 begin
     readln(m,n);
     num:=; sum:=;
     for i:= to m do
     begin
         for j:= to n do
         begin
             read(ch);
             if ch='.' then
             begin
                 map[i,j]:=(i-)*n+j;
                 inc(num);
             end
             else map[i,j]:=-;
         end;
         readln;
     end;
     for i:= to m do
         for j:= to n do
             if (map[i,j]>) and (cl[map[i,j]]=) then
                 dfs(i,j,);
     for i:= to m do
         for j:= to n do
                         if map[i,j]> then put(i,j);

     fillchar(l,sizeof(l),);
     fillchar(r,sizeof(r),);
         sum:=;
     for i:= to m*n do
         if cl[i]= then
         begin
             fillchar(pd,sizeof(pd),false);
              if Hungarian(i) then inc(sum);
         end;
     if sum*=num then
     begin
         writeln('LOSE');
         halt;
     end;
     writeln('WIN');
     fillchar(f,sizeof(f),);
     for i:= to m*n do
         if (cl[i]>) and (f[i]=) and (l[i]=) and (r[i]=) then
             if cl[i]= then dfsl(i) else dfsr(i);
     for i:=  to m do
         for j:= to n do
         begin
             x:=(i-)*m+j;
             if f[x]= then writeln(i,' ',j);
         end;
 end.

ps：好像没有LOSE的点 ←_ ←