标签:style blog http color os io ar for art
1 //Accepted 740 KB 15 ms 2 //树的直径 3 //距离一个顶点最远的点一定是树的直径的一个端点 4 #include <cstdio> 5 #include <cstring> 6 #include <queue> 7 #include <iostream> 8 using namespace std; 9 const int imax_n = 10005; 10 int dis[imax_n]; 11 int d1[imax_n]; 12 int d2[imax_n]; 13 int head[imax_n]; 14 int next[2*imax_n]; 15 int e; 16 struct node 17 { 18 int u,v,c; 19 node() 20 { 21 22 } 23 node(int u,int v,int c) 24 { 25 this->u=u; 26 this->v=v; 27 this->c=c; 28 } 29 }p[2*imax_n]; 30 int n; 31 void addEdge(int u,int v,int c) 32 { 33 p[e]=node(u,v,c); 34 next[e]=head[u]; 35 head[u]=e++; 36 } 37 void init() 38 { 39 memset(head,-1,sizeof(head)); 40 memset(next,-1,sizeof(next)); 41 e=0; 42 } 43 void read() 44 { 45 init(); 46 int x,y; 47 for (int i=2;i<=n;i++) 48 { 49 scanf("%d%d",&x,&y); 50 addEdge(i,x,y); 51 addEdge(x,i,y); 52 } 53 } 54 int max(int a,int b) 55 { 56 return a>b?a:b; 57 } 58 queue<int >q; 59 bool vis[imax_n]; 60 int bfs(int s) 61 { 62 //printf("111111\n"); 63 memset(dis,0,sizeof(dis)); 64 int ans=0; 65 int temp_node; 66 while (!q.empty()) q.pop(); 67 memset(vis,0,sizeof(vis[0])*(n+2)); 68 q.push(s); 69 vis[s]=1; 70 while (!q.empty()) 71 { 72 int x=q.front(); 73 if (dis[x]>ans) 74 { 75 ans=dis[x]; 76 temp_node=x; 77 } 78 q.pop(); 79 for (int i=head[x];i!=-1;i=next[i]) 80 { 81 int y=p[i].v; 82 if (!vis[y]) 83 { 84 vis[y]=1; 85 q.push(y); 86 if (dis[x]+p[i].c>dis[y]) 87 dis[y]=dis[x]+p[i].c; 88 } 89 } 90 } 91 return temp_node; 92 } 93 int main() 94 { 95 while (scanf("%d",&n)!=EOF) 96 { 97 read(); 98 int x=bfs(1); 99 x=bfs(x); 100 memcpy(d1,dis,sizeof(dis)); 101 bfs(x); 102 memcpy(d2,dis,sizeof(dis)); 103 for (int i=1;i<=n;i++) 104 { 105 printf("%d\n",max(d1[i],d2[i])); 106 } 107 } 108 return 0; 109 }
标签:style blog http color os io ar for art
原文地址:http://www.cnblogs.com/djingjing/p/3956682.html