bool match(int now){
  for(int i = 0; i < (int)g[now].size(); i++){
    if(vis[g[now][i]] || now == a && g[now][i] == b || 
       now == b && g[now][i] == a) continue;
    vis[g[now][i]] = 1;
    if(m[g[now][i]] == -1 || !vis[m[g[now][i]]] && match(m[g[now][i]]))
      { m[g[now][i]] = now; m[now] = g[now][i]; return true; }
  }
  return false;
}

//memset(m, -1, sizeof(m));
//for(int i = 0; i < n; i++)
//  if(m[i] == -1) memset(vis, 0, sizeof(vis)), match(i);

• Set ALLOWTOPICCHANGE = MatthewChan, YuryKholondyrev, SapphireJay