就是加一个1的下界就好了。

1 #include
     
       2 #define N 100005 3 #define LL long long 4 #define inf 0x3f3f3f3f 5 #define ls tr[x][0] 6 #define rs tr[x][1] 7 using namespace std; 8 inline int ra() 9 {10     int x=0,f=1; char ch=getchar();11     while (ch<'0' || ch>'9') {
   if (ch=='-') f=-1; ch=getchar();}12     while (ch>='0' && ch<='9') {x=x*10+ch-'0'; ch=getchar();}13     return x*f;14 }15 struct node{16     int c,v,from,to,next;17 }e[N];18 int tot=1,ans,from[N],n,m,S,T,head[N],cnt,dis[N],q[N<<1];19 bool inq[N];20 void ine(int x, int y, int v, int c)21 {22     e[++tot].to=y; e[tot].next=head[x]; head[x]=tot;23     e[tot].v=v; e[tot].c=c; e[tot].from=x;24 }25 void insert(int x, int y, int c, int v)26 {27     ine(x,y,v,c); ine(y,x,-v,0);28 }29 bool spfa()30 {31     for (int i=1; i<=n+2; i++) dis[i]=inf;32     int l=0,r=1; q[0]=S; dis[S]=0; inq[S]=1;33     while (l
      
       dis[x]+e[i].v && e[i].c)38             {39                 dis[e[i].to]=dis[x]+e[i].v;40                 from[e[i].to]=i;41                 if (!inq[e[i].to])42                 {43                     inq[e[i].to]=1;44                     q[r++]=e[i].to;45                 }46             }47         inq[x]=0;48     }49     if (dis[T]==inf) return 0;50     return 1;51 }52 void mcf()53 {54     int x=inf;55     for (int i=from[T];i;i=from[e[i].from]) x=min(x,e[i].c);56     for (int i=from[T];i;i=from[e[i].from]) ans+=x*e[i].v,e[i].c-=x,e[i^1].c+=x;57 }58 void fyl()59 {60     while (spfa()) mcf();61 }62 int main()63 {64     n=ra();65     S=n+1; T=n+2;66     for (int i=1; i<=n; i++)67     {68         int cnt=ra();69         insert(i,T,cnt,0);70         if (i!=1) insert(i,1,inf,0);71         for (int j=1; j<=cnt; j++)72         {73             int x=ra(),v=ra();74             insert(S,x,1,v);75             insert(i,x,inf,v);76         }77     }78     fyl();79     cout<