zoukankan      html  css  js  c++  java
  • Tree Cutting POJ

    After Farmer John realized that Bessie had installed a "tree-shaped" network among his N (1 <= N <= 10,000) barns at an incredible cost, he sued Bessie to mitigate his losses.

    Bessie, feeling vindictive, decided to sabotage Farmer John's network by cutting power to one of the barns (thereby disrupting all the connections involving that barn). When Bessie does this, it breaks the network into smaller pieces, each of which retains full connectivity within itself. In order to be as disruptive as possible, Bessie wants to make sure that each of these pieces connects together no more than half the barns on FJ.

    Please help Bessie determine all of the barns that would be suitable to disconnect.Input

    * Line 1: A single integer, N. The barns are numbered 1..N.

    * Lines 2..N: Each line contains two integers X and Y and represents a connection between barns X and Y.

    Output

    * Lines 1..?: Each line contains a single integer, the number (from 1..N) of a barn whose removal splits the network into pieces each having at most half the original number of barns. Output the barns in increasing numerical order. If there are no suitable barns, the output should be a single line containing the word "NONE".

    Sample Input

    10
    1 2
    2 3
    3 4
    4 5
    6 7
    7 8
    8 9
    9 10
    3 8

    Sample Output

    3
    8

    Hint

    INPUT DETAILS:

    The set of connections in the input describes a "tree": it connects all the barns together and contains no cycles.

    OUTPUT DETAILS:

    If barn 3 or barn 8 is removed, then the remaining network will have one piece consisting of 5 barns and two pieces containing 2 barns. If any other barn is removed then at least one of the remaining pieces has size at least 6 (which is more than half of the original number of barns, 5).
    数据比较水,求树的重心,固定套路
     1 #include<queue>
     2 #include<vector>
     3 #include<cstdio>
     4 #include<cstring>
     5 #include<iostream>
     6 #include<algorithm>
     7 using namespace std;
     8 
     9 const int maxn=1e4+5;
    10 
    11 struct node{
    12     int to,next;
    13 }e[4*maxn];
    14 
    15 int n,tot;
    16 int dp[maxn],num[maxn],head[maxn];
    17 
    18 void Inite(){
    19     tot=0;
    20     memset(head,-1,sizeof(head));
    21 } 
    22 
    23 void addedge(int u,int v){
    24     e[tot].to=v;
    25     e[tot].next=head[u];
    26     head[u]=tot++;
    27 }
    28 
    29 void DFS(int pa,int u){
    30     num[u]=1,dp[u]=0;
    31     for(int i=head[u];i!=-1;i=e[i].next){
    32         int v=e[i].to;
    33         if(pa==v) continue;
    34         DFS(u,v);
    35         dp[u]=max(dp[u],num[v]);
    36         num[u]+=num[v];
    37     } 
    38     dp[u]=max(dp[u],n-num[u]);
    39 }
    40 
    41 void Solve(){
    42     bool flag=false;
    43     for(int i=1;i<=n;i++){
    44         if(dp[i]<=n/2){
    45             flag=true;
    46             printf("%d
    ",i);
    47         }
    48     }
    49     if(!flag) printf("NONE
    ");
    50 }
    51 
    52 int main()
    53 {   Inite();
    54     scanf("%d",&n);
    55     for(int i=2;i<=n;i++){
    56         int u,v;
    57         scanf("%d%d",&u,&v);
    58         addedge(u,v);
    59         addedge(v,u);
    60     }
    61     DFS(0,1);
    62     Solve();
    63     
    64     return 0;
    65 }
  • 相关阅读:
    Oracle 用 sqlprompt 修改 sqlplus 提示符
    Oracle cursor pin S wait on X 等待事件 说明
    Oracle 利用 rowid 提升 update 性能
    Oracle 从缓存里面查找真实的执行计划
    Linux 进程状态 说明
    Oracle 用户 对 表空间 配额(quota ) 说明
    Upon startup of Linux database get ORA27102: out of memory LinuxX86_64 Error: 28: No space left on device
    异常宕机 Ora00600 [Kccpb_sanity_check_2] 错误解决方法
    Oracle ORA04031 错误 说明
    Oracle Shared pool 详解
  • 原文地址:https://www.cnblogs.com/zgglj-com/p/7748532.html
Copyright © 2011-2022 走看看