1 class Solution {
 2 public:
 3     typedef pair<int,int> pii;
 4     const int k1=1331;
 5     const int k2=13331;
 6     const int mod1=1e9+7;
 7     const int mod2=1e9+9;
 8     int p1[100005],p2[100005];
 9      struct pairhash {
10         size_t operator() (const pair<int, int>& p) const
 
 {
11             auto fn = hash<int>();
12             return (fn(p.first) <<16) ^ fn(p.second);
13         }
14     };
15 
16     int longestCommonSubpath(int n, vector<vector<int>>& paths) {
17          p1[0]=p2[0]=1;
18         for(int i=1;i<=100001;i++)
19         {
20             p1[i]=1ll*p1[i-1
 
]*k1%mod1;
21             p2[i]=1ll*p2[i-1]*k2%mod2;
22         }
23         int row=paths.size();
24         vector<int>s1[row+1];
25         vector<int>s2[row+1];
26         for(int i=1;i<=row;i++)s2[i]=s1[i]=vector<int>(paths[i-1].size()+1);
27         for(int i=1;i<=row;i++)
 
28         {
29             int sz=paths[i-1].size();
30             for(int j=1;j<=sz;j++)
31             {
32                 s1[i][j]=((1ll*s1[i][j-1]*k1%mod1)+paths[i-1][j-1])%mod1;
33                 s2[i][j]=((1ll*s2[i][j-1]*k2%mod2)+paths[i-1][j-1])%mod2;
34             }
35         }
36 
37         function<int(int)>check=[&](int len)
38         {
39             unordered_map<pii,int,pairhash>mp;
40            
41             for(int i=1;i+len-1<=paths[0].size();i++)
42             {
43                  int j=i+len-1;
44                  int x1=((s1[1][j]-(1ll*s1[1][i-1]*p1[j-i+1]%mod1))%mod1+mod1)%mod1;
45                  int x2=((s2[1][j]-(1ll*s2[1][i-1]*p2[j-i+1]%mod2))%mod2+mod2)%mod2;
46                  mp[{x1,x2}]=1;
47             }
48 
49             for(int x=2;x<=row;x++)
50             {
51                 unordered_map<pii,int,pairhash>vis;
52                 int sz=paths[x-1].size();
53                 bool ok=false;
54                 for(int i=1;i+len-1<=sz;i++)
55                 {
56                     int j=i+len-1;
57                     int t1=((s1[x][j]-(1ll*s1[x][i-1]*p1[j-i+1]%mod1))%mod1+mod1)%mod1;
58                     int t2=((s2[x][j]-(1ll*s2[x][i-1]*p2[j-i+1]%mod2))%mod2+mod2)%mod2;
59                     if(mp[{t1,t2}]&&!vis[{t1,t2}]){mp[{t1,t2}]++;vis[{t1,t2}]=1;}
60                 }    
61             }
62             for(auto &p:mp)if(p.second==row)return 1;
63             return 0;
64         };
65         int l=0,r=1e6;
66         while(l<=r)
67         { 
68             int mid=(l+r)>>1;
69             if(check(mid))l=mid+1;
70             else r=mid-1;
71         }
72         return r;
73     }
74 };