[Bzoj1854] game

Consider the arms (a, b) as an undirected edges, then for a communication block
1. When there is no ring, means one tree, then optionally a point as a root, each edge node can only select son, obviously root to choose the largest number
2. when there is a ring, the ring optionally as a root, a side of a ring to rest on the ring so as to become removed a tree, the tree edge selection sons rims a certain order can be selected
then the subject is equivalent to the minimum required to maintain a maximum number of the tree for each block communicating with disjoint-set to maintain

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 int n,x,y,ans,f[1000005],vis[1000005];
 4 int find(int k){
 5     if (k==f[k])return k;
 6     return f[k]=find(f[k]);
 7 }
 8 int main(){
 9     scanf("%d",&n);
10     for(int i=1;i<=n+1;i++)f[i]=i;
11     for(int i=1;i<=n;i++){
12         scanf("%d%d",&x,&y);
13         if (find(x)==find(y))vis[find(x)]=1;
14         else{
15             if (find(x)>find(y))swap(x,y);
16             vis[find(y)]|=vis[find(x)];
17             vis[find(x)]=1;
18             f[find(x)]=find(y);
19         }
20     }
21     ans=1 ;
22      while (screw [years]) years ++ ;
23      printf ( " % d " , ans- 1 );
24 }

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