Gym 101334C 无向仙人掌

  1 #include <bits/stdc++.h>
  2 
  3 using namespace std;
  4 
  5 const int maxn = 20000 + 5;
  6 
  7 struct Sol {
  8     vector<int> G[maxn];
  9     int cyclecnt;
 10     int cycle[maxn];
 11     int dfn[maxn];
 12     int c[maxn];
 13     int n;
 14     int num[maxn];
 15 
 16     void init(int n) {
 17         this->n = n;
 18         for(int i=0; i<=n; i++)
 19             G[i].clear();
 20         memset(dfn,0,sizeof(dfn));
 21         memset(cycle,0,sizeof(cycle));
 22         memset(num,0,sizeof(num));
 23         cyclecnt = 0;
 24         dfn[1] = 1;
 25     }
 26 
 27     void AddEdge (int from,int to) {
 28         G[from].push_back(to);
 29         G[to].push_back(from);
 30     }
 31 
 32     void dfs(int u,int fa) {
 33         for(int i=0; i<G[u].size(); i++) {
 34             int v = G[u][i];
 35             if(v==fa) continue;
 36 
 37             if(!dfn[v]) {
 38                 dfn[v] = dfn[u] + 1;
 39                 dfs(v,u);
 40                 c[u]+=c[v];
 41             } else if(dfn[v]<dfn[u]) {
 42                 cycle[cyclecnt++] = dfn[u] - dfn[v] + 2;
 43                 c[u]++;
 44                 c[v]--;
 45             }
 46         }
 47     }
 48 
 49     void ans() {
 50         for(int i=1; i<=n; i++)
 51             if(c[i]>1||dfn[i]==0) {
 52                 puts("0");
 53                 return;
 54             }
 55         //int res = 1;
 56         //for(int i=0;i<cyclecnt;i++)
 57         //    res = res * cycle[i];
 58         //return res;
 59 
 60         int len = 0;
 61         num[0] = 1;
 62 
 63         for(int i=0; i<cyclecnt; i++) {
 64 
 65             for(int j=0; j<=len; j++)
 66                 num[j] = num[j]*cycle[i];
 67 
 68             for(int j=0; j<=len; j++) {
 69                 num[j+1] += num[j]/10;
 70                 num[j] = num[j]%10;
 71             }
 72             while(num[len+1]) {
 73                 num[len+2]+=num[len+1]/10;
 74                 num[++len]%=10;
 75             }
 76         }
 77 
 78         for(int i=len; i>=0; i--)
 79             printf("%d",num[i]);
 80         puts("");
 81     }
 82 
 83 
 84 
 85 } sol;
 86 
 87 int main() {
 88     freopen("cactus.in","r",stdin);
 89     freopen("cactus.out","w",stdout);
 90     int n,m;
 91     scanf("%d%d",&n,&m);
 92 
 93     sol.init(n);
 94 
 95     for(int i=0; i<m; i++) {
 96         int k,u;
 97         scanf("%d%d",&k,&u);
 98         for(int i=0; i<k-1; i++) {
 99             int v;
100             scanf("%d",&v);
101             sol.AddEdge(u,v);
102             u = v;
103         }
104     }
105 
106     sol.dfs(1,-1);
107 
108     sol.ans();
109 
110     //printf("%d\n",sol.ans());
111 
112     return 0;
113 }