bzoj 3876: [Ahoi2014]支线剧情

 就是加一个1的下界就好了。

#include<bits/stdc++.h>
#define N 100005
#define LL long long
#define inf 0x3f3f3f3f
#define ls tr[x][0]
#define rs tr[x][1]
using namespace std;
inline int ra()
{
    int x=0,f=1; char ch=getchar();
    while (ch<'0' || ch>'9') {if (ch=='-') f=-1; ch=getchar();}
    while (ch>='0' && ch<='9') {x=x*10+ch-'0'; ch=getchar();}
    return x*f;
}
struct node{
    int c,v,from,to,next;
}e[N];
int tot=1,ans,from[N],n,m,S,T,head[N],cnt,dis[N],q[N<<1];
bool inq[N];
void ine(int x, int y, int v, int c)
{
    e[++tot].to=y; e[tot].next=head[x]; head[x]=tot;
    e[tot].v=v; e[tot].c=c; e[tot].from=x;
}
void insert(int x, int y, int c, int v)
{
    ine(x,y,v,c); ine(y,x,-v,0);
}
bool spfa()
{
    for (int i=1; i<=n+2; i++) dis[i]=inf;
    int l=0,r=1; q[0]=S; dis[S]=0; inq[S]=1;
    while (l<r)
    {
        int x=q[l++];
        for (int i=head[x];i;i=e[i].next)
            if (dis[e[i].to]>dis[x]+e[i].v && e[i].c)
            {
                dis[e[i].to]=dis[x]+e[i].v;
                from[e[i].to]=i;
                if (!inq[e[i].to])
                {
                    inq[e[i].to]=1;
                    q[r++]=e[i].to;
                }
            }
        inq[x]=0;
    }
    if (dis[T]==inf) return 0;
    return 1;
}
void mcf()
{
    int x=inf;
    for (int i=from[T];i;i=from[e[i].from]) x=min(x,e[i].c);
    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;
}
void fyl()
{
    while (spfa()) mcf();
}
int main()
{
    n=ra();
    S=n+1; T=n+2;
    for (int i=1; i<=n; i++)
    {
        int cnt=ra();
        insert(i,T,cnt,0);
        if (i!=1) insert(i,1,inf,0);
        for (int j=1; j<=cnt; j++)
        {
            int x=ra(),v=ra();
            insert(S,x,1,v);
            insert(i,x,inf,v);
        }
    }
    fyl();
    cout<<ans;
    return 0;
}