http://codeforces.com/contest/842/problem/C

樹 dp

一個數的質因數有限，用set存儲，去重

  1 #include <cstdio>
  2 #include <cstdlib>
  3 #include <cmath>
  4 #include <cstring>
  5 #include <time.h>
  6 #include <string>
  7 #include <set>
  8 #include <map>
  9 #include <list>
 10
 
 #include <stack>
 11 #include <queue>
 12 #include <vector>
 13 #include <bitset>
 14 #include <ext/rope>
 15 #include <algorithm>
 16 #include <iostream>
 17 using namespace std;
 18 #define ll long long
 19 #define minv 1e-6
 20 #define inf 1e9
 21 #define pi 3.1415926536
 22
 
 #define E  2.7182818284
 23 const ll mod=1e9+7;//998244353
 24 const int maxn=2e5+10;
 25 
 26 struct node
 27 {
 28     int d;
 29     node* next;
 30 }*e[maxn];
 31 
 32 set<int>y[maxn]; //delete one
 33 int a[maxn],x[maxn],value[maxn];
 34 bool vis[maxn]={0};
 35 
 36 void dfs(int d)
 37 {
 38     set
 
<int>::iterator i;
 39     int dd;
 40 
 41     value[d]=x[d];
 42     for (i=y[d].begin();i!=y[d].end();i++)
 43         value[d]=max(value[d],*i);
 44 
 45     node* p=e[d];
 46     vis[d]=1;
 47     while (p)
 48     {
 49         dd=p->d;
 50         if (!vis[dd])
 51         {
 52             x[dd]=__gcd(x[d],a[dd]);
 53             y[dd].insert(x[d]);
 54             for (i=y[d].begin();i!=y[d].end();i++)
 55                 y[dd].insert(__gcd(a[dd],*i));
 56             if (d==1)
 57                 y[dd].insert(a[dd]);
 58             dfs(dd);
 59         }
 60         p=p->next;
 61     }
 62     //free memory
 63     y[d].clear();
 64 }
 65 
 66 int main()
 67 {
 68     node* p;
 69     int n,X,y,i;
 70     scanf("%d",&n);
 71     for (i=1;i<=n;i++)
 72         scanf("%d",&a[i]);
 73     for (i=1;i<n;i++)
 74     {
 75         scanf("%d%d",&X,&y);
 76         p=(node*) malloc (sizeof(node));
 77         p->d=y;
 78         p->next=e[X];
 79         e[X]=p;
 80 
 81         p=(node*) malloc (sizeof(node));
 82         p->d=X;
 83         p->next=e[y];
 84         e[y]=p;
 85     }
 86 
 87     x[1]=a[1];
 88     dfs(1);
 89 
 90     for (i=1;i<n;i++)
 91         printf("%d ",value[i]);
 92     printf("%d",value[i]);
 93     return 0;
 94 }
 95 /*
 96 3
 97 6 10 12
 98 1 2
 99 2 3
100 */

C - Ilya And The Tree Codeforces Round #430 (Div. 2)