洛谷1983（DAG上最长路）

传送门
停车点连向不停车点，重复的边只连一次，最后求一个DAG（有向无环图）上最长路即可。

#include<cstdio>#include<cstring>#include<iostream>#include<algorithm>#include<cstdlib>using namespace std;const int maxn=1002;int n,m;int head[maxn],edge;struct EDGE {    int v,nxt;}e[maxn*maxn];int vis[maxn][maxn],t[maxn];inline int read() {    int x=0,f=1;char c=getchar();    while (c<'0'||c>'9') {if (c=='-') f=-1;c=getchar();}    while (c>='0'&&c<='9') x=x*10+c-'0',c=getchar();    return x*f;}inline void adde(int u,int v) {    e[edge].v=v,e[edge].nxt=head[u],head[u]=edge++;}int f[maxn];int dfs(int p) {    for (int i=head[p];~i;i=e[i].nxt) {        int v=e[i].v;        f[p]=max(f[p],f[v]?f[v]:f[v]=dfs(v));    }    return ++f[p];}int main() {//  freopen("P1983.in","r",stdin);    while (~scanf("%d%d",&n,&m)) {        memset(t,0,sizeof(t));        memset(vis,0,sizeof(vis));        memset(f,0,sizeof(f));        memset(head,-1,sizeof(head)),edge=0;        while (m--) {            int num=read();            for (int i=1;i<=num;++i) t[i]=read();            int s=1;            for (int i=t[1];i<t[num];++i)                if (t[s]==i) ++s;                else                    for (int j=1;j<=num;++j)                        if (!vis[t[j]][i])                            vis[t[j]][i]=1,adde(t[j],i);        }        int res=0;        for (int i=1;i<=n;++i)            if (!f[i]) res=max(res,f[i]=dfs(i));        printf("%d\n",res);    }    return 0;}