车站分级
https://www.luogu.org/problemnew/show/P1983
題解:拓撲排序
參考文章:https://blog.csdn.net/weixin_43272781/article/details/87918994
/* *@Author: STZG *@Language: C++ */ #include <bits/stdc++.h> #include<iostream> #include<algorithm> #include<cstdlib> #include<cstring> #include<cstdio> #include<string> #include<vector> #include<bitset> #include<queue> #include<deque> #include<stack> #include<cmath> #include<list> #include<map> #include<set> //#define DEBUG #define RI register int using namespace std; typedef long long ll; //typedef __int128 lll; const int N=1000+10; const int M=100000+10; const int MOD=1e9+7; const double PI = acos(-1.0); const double EXP = 1E-8; const int INF = 0x3f3f3f3f; int t,n,m,k,q; int ans,cnt,flag,temp,sum; int a[N]; bool vis[N][N]; bool is[N]; char str; struct node{}; int in[N]; int dep[N]; vector<int>G[N]; void topo(){queue<int>q;for(int i=1;i<=n;i++){if(!in[i]){q.push(i);dep[i]=1;}}while(!q.empty()){int u=q.front();q.pop();for(int i=0,j=G[u].size();i<j;i++){int v=G[u][i];dep[v]=dep[u]+1;ans=max(ans,dep[v]);in[v]--;if(!in[v])q.push(v);}}} int main() { #ifdef DEBUGfreopen("input.in", "r", stdin);//freopen("output.out", "w", stdout); #endif//ios::sync_with_stdio(false);//cin.tie(0);//cout.tie(0);//scanf("%d",&t);//while(t--){scanf("%d%d",&n,&m);for(int i=1;i<=m;i++){scanf("%d",&k);memset(a,0,sizeof(a));memset(is,0,sizeof(is));for(int j=1;j<=k;j++){scanf("%d",&a[j]);is[a[j]]=1;}for(int j=a[1];j<=a[k];j++){if(!is[j]){for(int p=1;p<=n;p++){if(!vis[j][a[p]]){in[a[p]]++;G[j].push_back(a[p]);vis[j][a[p]]=1;}}}}}topo();cout<<ans<<endl;//}#ifdef DEBUGprintf("Time cost : %lf s\n",(double)clock()/CLOCKS_PER_SEC); #endif//cout << "Hello world!" << endl;return 0; }?
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