1 #include <iostream>
 2 #include <set>
 3 #include <vector>
 4 #define _for(i,a,b) for(int i = (a);i < (b);i ++)
 5
 6 using namespace std;
 7
 8 const int maxn = 100039;
 9 set<int> g[maxn];
10 vector<int> f[maxn];
11 bool fvis[maxn] {0},gvis[maxn] {0};
12 class Solution
13 {
14     public:
15         void demo(int x,int id)
16         {
17             for(int i = 2;i*i <= x;i ++)
18             {
19                 if(!(x%i))
20                 {
21                     f[id].push_back(i);//factor in vector
22                     g[i].insert(id);//index in set
23                     while(!(x%i)) x /= i;
24                 }
25             }
26             if(x>1)
27             {
28                 f[id].push_back(x);//factor in vector
29                 g[x].insert(id);//index in set
30             }
31         }
32         void dfs(int id,set<int> &S)
33         {
34             fvis[id] = true;
35             S.insert(id);
36             for(auto fac:f[id])
37             {
38                 if(gvis[fac]) continue;
39                 gvis[fac] = true;
40                 for(auto fidx:g[fac])
41                 {
42                     if(fvis[fidx]) continue;
43                     S.insert(fidx);
44                     dfs(fidx,S);
45                 }
46             }
47         }
48         int largestComponentSize(vector<int>& A)
49         {
50             _for(i,0,A.size())
51                 demo(A[i],i);
52             int rnt = 1;
53             _for(i,0,A.size())
54             {
55                 set<int> tmp;
56                 if(fvis[i]) continue;
57                 dfs(i,tmp);
58                 rnt = max(rnt,(int)tmp.size());
59             }
60             return rnt;
61         }
62 };
63 int main()
64 {
65     Solution obj;
66     vector<int> A {2,3,6,7,4,12,21,39};
67     cout << obj.largestComponentSize(A) << endl;
68     return 0;
69 }