求助，50分

应该没问题啊

#include<bits/stdc++.h>
using namespace std;
const int mxn=2e6+5;
int n,m,s,flag,cnt,col,ins[mxn],dfn[mxn],low[mxn],bl[mxn];
vector<int >g[mxn];stack<int >st;
string s1,s2;
inline int read()
{
    char c=getchar();int x=0,f=1;
    while(c>'9'||c<'0') {if(c=='-') f=-1;c=getchar();}
    while(c>='0'&&c<='9') {x=(x<<3)+(x<<1)+(c^48);c=getchar();}
    return x*f;
}
void tj(int u)
{
    dfn[u]=low[u]=++s,st.push(u),ins[u]=1;
    for(int i=0;i<g[u].size();++i){
        int v=g[u][i];
        if(!dfn[v]) tj(v),low[u]=min(low[u],low[v]);
        else if(ins[v]) low[u]=min(dfn[v],low[u]);
    }
    if(dfn[u]==low[u]){
        ++cnt;
        do{
            bl[u]=cnt;
            u=st.top();
            st.pop();
            ins[u]=0;
        } while(low[u]!=dfn[u]);
    }
}

int main()
{
    int T;cin>>T;
    int x,y,xi,yi;
    while(T--){
        memset(dfn,0,sizeof(dfn));
        memset(low,0,sizeof(low));
        memset(bl,0,sizeof(bl));memset(ins,0,sizeof(bl));
        //memset(bl,0,sizeof(bl));
        col=cnt=s=0;

//  n=read(),m=read();
    cin>>n>>m;
        for(int i=1;i<=m;++i){
    //  x=read(),xi=read(),y=read(),yi=read();
        cin>>s1>>s2;
        x=s1[1]-'0',xi=(s1[0]=='m' ? 1 : 0);y=s2[1]-'0';yi=(s2[0]=='m'?1:0);
    //  cout<<s1[0];
        g[x+n*(xi^1)].push_back(y+yi*n);
        g[y+n*(yi^1)].push_back(x+xi*n);
    }   
    flag=0;
    for(int i=1;i<=2*n;++i) if(!dfn[i]) tj(i);
    while(!st.empty()) st.pop();
    for(int i=1;i<=n*2;++i) g[i].clear();
    for(int i=1;i<=n;++i) 
        if(bl[i]==bl[i+n]) {
            printf("BAD\n");

            flag=1;
            break;
        }
    if(flag==0)
    printf("GOOD\n");
/// for(int i=1;i<=n*2;++i)
//      printf("%d ",bl[i]);
//  }
}
    return 0;
}