A graph which is connected and acyclic can be considered a tree. The height of the tree depends on the selected root. Now you are supposed to find the root that results in a highest tree. Such a root is called the deepest root.
Input Specification:
Each input file contains one test case. For each case, the first line contains a positive integer N (<=10000) which is the number of nodes, and hence the nodes are numbered from 1 to N. Then N-1 lines follow, each describes an edge by given the two adjacent nodes' numbers.
Output Specification:
For each test case, print each of the deepest roots in a line. If such a root is not unique, print them in increasing order of their numbers. In case that the given graph is not a tree, print "Error: K components" where K is the number of connected components in the graph.
Sample Input 1:
5
1 2
1 3
1 4
2 5
Sample Output 1:
3
4
5
Sample Input 2:
5
1 3
1 4
2 5
3 4
Sample Output 2:
Error: 2 components
1 #include <iostream> 2 3 #include <vector> 4 5 #include <queue> 6 7 using namespace std; 8 9 vector<int> adj[10001]; 10 int visit[10001]; 11 int Tree[10001]; 12 int root[10001]; 13 int MM[10001]; 14 int num; 15 int getroot(int x) 16 17 { 18 19 if(Tree[x]==-1) return x; 20 21 else 22 23 { 24 int tem=getroot(Tree[x]); 25 Tree[x]=tem; 26 return tem; 27 } 28 29 } 30 31 32 33 34 35 void DFS(int x,int d) 36 37 { 38 visit[x]=1; 39 int i; 40 for(i=0;i<adj[x].size();i++) 41 { 42 43 if(visit[adj[x][i]]==0) 44 DFS(adj[x][i],d+1); 45 } 46 root[num++]=d; 47 } 48 49 50 51 52 53 54 55 56 57 int main() 58 59 { 60 int n,a,b,i,j; 61 while(cin>>n) 62 { 63 for(i=1;i<=n;i++)//初始化 64 { 65 Tree[i]=-1; 66 adj[i].clear(); 67 } 68 for(i=0;i<n-1;i++) 69 { 70 cin>>a>>b; 71 adj[a].push_back(b); 72 adj[b].push_back(a); 73 a=getroot(a);//并查集 74 b=getroot(b); 75 if(a!=b) 76 { 77 Tree[a]=b; 78 } 79 } 80 int count=0;//极大连通图个数 81 for(i=1;i<=n;i++) 82 { 83 if(Tree[i]==-1) count++; 84 } 85 if(count!=1) 86 { 87 cout<<"Error: "<<count<<" components"<<endl;//不是树 88 } 89 else 90 { 91 for(i=1;i<=n;i++) 92 { 93 for(j=1;j<=n;j++)//每次查找都要初始化 94 visit[j]=0; 95 num=0; 96 DFS(i,1); 97 MM[i]=0; 98 for(j=0;j<num;j++) 99 { 100 if(MM[i]<root[j]) 101 MM[i]=root[j]; 102 } 103 } 104 int max=0; 105 for(i=1;i<=n;i++) 106 { 107 if(max<MM[i]) 108 max=MM[i]; 109 } 110 for(i=1;i<=n;i++) 111 { 112 if(max==MM[i]) 113 cout<<i<<endl; 114 } 115 } 116 } 117 return 0; 118 }