zoukankan      html  css  js  c++  java
  • POJ1155 TELE

    Time Limit: 1000MS   Memory Limit: 65536K
    Total Submissions: 4976   Accepted: 2734

    Description

    A TV-network plans to broadcast an important football match. Their network of transmitters and users can be represented as a tree. The root of the tree is a transmitter that emits the football match, the leaves of the tree are the potential users and other vertices in the tree are relays (transmitters). 
    The price of transmission of a signal from one transmitter to another or to the user is given. A price of the entire broadcast is the sum of prices of all individual signal transmissions. 
    Every user is ready to pay a certain amount of money to watch the match and the TV-network then decides whether or not to provide the user with the signal. 
    Write a program that will find the maximal number of users able to watch the match so that the TV-network's doesn't lose money from broadcasting the match.

    Input

    The first line of the input file contains two integers N and M, 2 <= N <= 3000, 1 <= M <= N-1, the number of vertices in the tree and the number of potential users. 
    The root of the tree is marked with the number 1, while other transmitters are numbered 2 to N-M and potential users are numbered N-M+1 to N. 
    The following N-M lines contain data about the transmitters in the following form: 
    K A1 C1 A2 C2 ... AK CK 
    Means that a transmitter transmits the signal to K transmitters or users, every one of them described by the pair of numbers A and C, the transmitter or user's number and the cost of transmitting the signal to them. 
    The last line contains the data about users, containing M integers representing respectively the price every one of them is willing to pay to watch the match.

    Output

    The first and the only line of the output file should contain the maximal number of users described in the above text.

    Sample Input

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

    Sample Output

    5

    Source

    树形DP,f[当前结点][连接的客户端数]=花费

    最后对f[根节点][j]扫描,找到使f为正的最大j,即是答案。

     1 /*by SilverN*/
     2 #include<iostream>
     3 #include<algorithm>
     4 #include<cstring>
     5 #include<cstdio>
     6 #include<cmath>
     7 using namespace std;
     8 const int INF=0x3f3f3f3f;
     9 const int mxn=3200;
    10 struct edge{
    11     int v,dis;
    12     int nxt;
    13 }e[mxn];
    14 int hd[mxn],cnt=0;
    15 void add_edge(int u,int v,int dis){
    16     e[++cnt].v=v;e[cnt].dis=dis;e[cnt].nxt=hd[u];hd[u]=cnt;
    17     return;
    18 }
    19 int n,m;
    20 int num[mxn];
    21 int f[mxn][mxn];
    22 void dp(int u){
    23     int i,j,k;
    24     for(i=hd[u];i;i=e[i].nxt){
    25         int v=e[i].v;
    26         dp(v);
    27         num[u]+=num[v];
    28         for(j=num[u];j;--j){
    29             for(k=num[v];k;--k){
    30                 f[u][j]=max(f[u][j],f[u][j-k]+f[v][k]-e[i].dis);
    31             }
    32         }
    33     }
    34     return;
    35 }
    36 int main(){
    37     scanf("%d%d",&n,&m);
    38     int i,j,k;
    39     int u,v,d;
    40     for(i=1;i<=n-m;i++){
    41         scanf("%d",&k);
    42         for(j=1;j<=k;j++){    
    43             scanf("%d%d",&v,&d);
    44             add_edge(i,v,d);
    45         }
    46     }
    47     for(i=1;i<=n;i++)
    48      for(j=1;j<=m;j++)
    49          f[i][j]=-INF;
    50     for(i=n-m+1;i<=n;i++){num[i]=1;scanf("%d",&f[i][1]);}
    51     dp(1);
    52     for(i=m;i>=0;i--){
    53         if(f[1][i]>=0){
    54             printf("%d
    ",i);
    55             break;
    56         }
    57     }
    58     return 0;
    59 }
  • 相关阅读:
    cocos2dx中的精灵CCSprite
    Mark Russinovich 的博客:Windows Azure 主机更新:原因、时间和方式
    cocos2d-x中的尺寸之三
    cocos2d-x中的尺寸之二
    cocos2d-x中的尺寸之一
    cocos2d-x中的导演、场景、层和精灵
    宣布正式发布 Windows Azure 上的 Oracle 软件以及 Windows Azure Traffic Manager 更新
    Hello China操作系统STM32移植指南(三)
    Hello China操作系统STM32移植指南(二)
    diff_mysql_table_exec.py
  • 原文地址:https://www.cnblogs.com/SilverNebula/p/5916227.html
Copyright © 2011-2022 走看看