思路比较迷……题解在

//minamoto#include
    
     #define R register#define fp(i,a,b) for(R int i=a,I=b+1;i
     
      I;--i)#define go(u) for(int i=head[u],v=e[i].v;i;i=e[i].nx,v=e[i].v)using namespace std;int read(){    R int res,f=1;R char ch;    while((ch=getchar())>'9'||ch<'0')(ch=='-')&&(f=-1);    for(res=ch-'0';(ch=getchar())>='0'&&ch<='9';res=res*10+ch-'0');    return res*f;}const int N=105,M=10005;const int dx[]={1,0,-1,0},dy[]={0,1,0,-1};struct eg{int v,nx;}e[M];int head[M],tot;inline void add(R int u,R int v){e[++tot]={v,head[u]},head[u]=tot;}int id[N][N],vis[M],st[M],match[M];bool ban[M],win[M],mp[N][N];int n,m,tim,top,cnt,q,bx,by;char s[N];bool find(int u){    if(ban[u])return 0;go(u){        if(vis[v]==tim||ban[v])continue;        vis[v]=tim;if(!match[v]||find(match[v])){            match[u]=v,match[v]=u;return 1;        }    }return 0;}int main(){//  freopen("testdata.in","r",stdin);    n=read(),m=read();    fp(i,1,n){        scanf("%s",s+1);        fp(j,1,m)switch(s[j]){            case 'X':mp[i][j]=1;break;            case 'O':mp[i][j]=0;break;            case '.':mp[i][j]=1,bx=i,by=j;break;        }    }fp(i,1,n)fp(j,1,m)id[i][j]=++cnt;    fp(i,1,n)fp(j,1,m)if(mp[i][j])fp(k,0,3){        int x=i+dx[k],y=j+dy[k];        if(x>=1&&x<=n&&y>=1&&y<=m&&!mp[x][y])add(id[i][j],id[x][y]),add(id[x][y],id[i][j]);    }fp(i,1,n)fp(j,1,m)if(mp[i][j])++tim,find(id[i][j]);    q=read();fp(i,1,(q<<1)){        int x=id[bx][by];ban[x]=1;        if(match[x]){            int y=match[x];match[x]=match[y]=0;            ++tim,win[i]=!find(y);        }bx=read(),by=read();    }    fp(i,1,q)if(win[(i<<1)-1]&&(win[i<<1]))st[++top]=i;    printf("%d\n",top);fp(i,1,top)printf("%d\n",st[i]);    return 0;}