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[1..4] of longint=(0,0,-1,1);
      dy:array[1..4] of longint=(1,-1,0,0);
      maxn=100008;
      maxm=maxn*4;
var map:array[0..108,0..108] of longint;
    cl:array[0..maxn] of longint;
    eg:array[0..maxm] of arr;
    last:array[0..maxn] of longint;
    l,r,f:array[0..maxn] of longint;
    pd:array[0..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:=1 to 4 do
    begin
        x:=i+dx[k]; y:=j+dy[k];
        if (map[x,y]>0) and (cl[map[x,y]]=0) then
            dfs(x,y,3-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:=1 to 4 do
    begin
        x:=i+dx[k]; y:=j+dy[k];
        if (map[x,y]>0) 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<>0 do
    begin
        v:=eg[i].v;
        if not pd[v] then
        begin
            pd[v]:=true;
            if (l[v]=0) 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]:=2;
    i:=last[u];
    while i<>0 do
    begin
        v:=eg[i].v;
        if f[v]=0 then
        begin
            f[v]:=1;
            if f[l[v]]=0 then dfsl(l[v]);
        end;
        i:=eg[i].next;
    end;
end;

procedure dfsr(u:longint);
var i,v:longint;
begin
    f[u]:=2;
    i:=last[u];
    while i<>0 do
    begin
        v:=eg[i].v;
        if f[v]=0 then
        begin
            f[v]:=1;
            if f[r[v]]=0 then dfsr(r[v]);
        end;
        i:=eg[i].next;
    end;
end;
begin
    readln(m,n);
    num:=0; sum:=0;
    for i:=1 to m do
    begin
        for j:=1 to n do
        begin
            read(ch);
            if ch='.' then
            begin
                map[i,j]:=(i-1)*n+j;
                inc(num);
            end
            else map[i,j]:=-1;
        end;
        readln;
    end;
    for i:=1 to m do
        for j:=1 to n do
            if (map[i,j]>0) and (cl[map[i,j]]=0) then
                dfs(i,j,1);
    for i:=1 to m do
        for j:=1 to n do
                        if map[i,j]>0 then put(i,j);

    fillchar(l,sizeof(l),0);
    fillchar(r,sizeof(r),0);
        sum:=0;
    for i:=1 to m*n do
        if cl[i]=1 then
        begin
            fillchar(pd,sizeof(pd),false);
             if Hungarian(i) then inc(sum);
        end;
    if sum*2=num then
    begin
        writeln('LOSE');
        halt;
    end;
    writeln('WIN');
    fillchar(f,sizeof(f),0);
    for i:=1 to m*n do
        if (cl[i]>0) and (f[i]=0) and (l[i]=0) and (r[i]=0) then
            if cl[i]=1 then dfsl(i) else dfsr(i);
    for i:= 1 to m do
        for j:=1 to n do
        begin
            x:=(i-1)*m+j;
            if f[x]=2 then writeln(i,' ',j);
        end;
end.

 ps：好像没有LOSE的点 ←_ ←