CSU1633: Landline Telephone Network
2015-05-25 14:41
190 查看
Description
The mayor of RMRCity wants to create a secure landline telephone network for emergency use in case of serious disasters when the city is cut off from the outside world. Some pairs of buildings in the city can be directly connected with a wire telephone lineand the municipality engineers have prepared an estimate of the cost of connecting any such pair.
The mayor needs your help to find the cheapest network that connects all buildings in the city and satisfies a particular security measure that will be explained shortly. A call from a building A to another building B may be routed through any simple path in
the network (i.e., a path that does not have any repeated building). There are also some insecure buildings that one or more persons with serious criminal records live in. The mayor wants only communications intended for these insecure buildings to reach them.
In other words, no communication from any building A to any building B should pass through any insecure building C in the network (where C is different from A and B).
Input
The input consists of a single test case. The first line contains three integers n, m, p where 1 ≤ n ≤ 1000 is the number of buildings, 0 ≤ m ≤ 100000 is the number of possible direct connections between a pair of buildings, and 0 ≤ p ≤ n is the number ofinsecure buildings. The buildings are numbered from 1 to n.
The second line contains p distinct integers between 1 and n (inclusive), which are the numbers of insecure buildings. Each of the next m lines contains three integers xi, yi, and li describing one potential direct line, where xi and yi (1 ≤ xi, yi ≤ n) are
the distinct buildings the line connects, and li (1 ≤ li ≤ 10000) is the estimate of the cost of connecting these buildings. There is at most one direct link between any two buildings in these m lines.
Output
Display the cost of the cheapest network satisfying the security measure if it is possible. Otherwise, displayimpossible.
Sample Input
4 6 1 1 1 2 1 1 3 1 1 4 1 2 3 2 2 4 4 3 4 3
Sample Output
6
HINT
Source
题意:给出一个图,但是又的点是不安全的,现在要求建成一颗树,让不安全的点全部做叶子节点,输出最小花费思路:先把所有安全点并查集成一颗树,再把不安全节点一个个的连上去
#include <iostream> #include <stdio.h> #include <string.h> #include <stack> #include <queue> #include <map> #include <set> #include <vector> #include <math.h> #include <bitset> #include <algorithm> #include <climits> using namespace std; #define LS 2*i #define RS 2*i+1 #define UP(i,x,y) for(i=x;i<=y;i++) #define DOWN(i,x,y) for(i=x;i>=y;i--) #define MEM(a,x) memset(a,x,sizeof(a)) #define W(a) while(a) #define gcd(a,b) __gcd(a,b) #define LL long long #define N 25 #define MOD 1000000007 #define INF 0x3f3f3f3f #define EXP 1e-8 struct node { int u,v,w; } e[100005]; int father[1005],vis[1005],cnt[1005]; int n,m,p; int cmp(node a,node b) { return a.w<b.w; } int find(int x) { if(x == father[x]) return x; return father[x]=find(father[x]); } int main() { int i,j,k,x,y,u,v,w,flag,ans; W(~scanf("%d%d%d",&n,&m,&p)) { flag = ans = 0; MEM(vis,0); MEM(cnt,0); UP(i,1,n) father[i]=i; UP(i,1,p) { scanf("%d",&x); vis[x] = 1; } UP(i,1,m) { scanf("%d%d%d",&u,&v,&w); e[i].u=u; e[i].v=v; e[i].w=w; } if(n==2) { printf("%d\n",w); continue; } sort(e+1,e+1+m,cmp); UP(i,1,m) { u = e[i].u,v=e[i].v,w=e[i].w; if(vis[u]||vis[v]) continue; x = find(u),y = find(v); if(x==y) continue; father[x] = y; ans+=w; } UP(i,1,m) { u = e[i].u,v=e[i].v,w=e[i].w; if(!(vis[u]^vis[v])) continue; cnt[u]++; cnt[v]++; if(vis[u]&&cnt[u]>=2) continue; if(vis[v]&&cnt[v]>=2) continue; x = find(u),y = find(v); if(x==y) continue; father[x] = y; ans+=w; } UP(i,1,n) { if(father[i]==i) flag++; } if(flag>=2) printf("impossible\n"); else printf("%d\n",ans); } return 0; }
相关文章推荐
- CSU 1633: Landline Telephone Network (最小生成树)
- PSTN ( Public Switched Telephone Network )
- 看An incremental network for on-line unsupervised classification and topology learning
- WA : csu1019 simple line editor
- linux probe whether network line is attached to network card normally
- csu 1019 Simple Line Editor
- Commandline-guide to virtual network settings and more
- CSU1019-Simple Line Editor-模拟
- BROADBAND POWERLINE COMMUNICATIONS NETWORK DESIGN:宽带电力线通信网络设计
- 【读论文】唐建LINE那篇论文:LINE: Large-scale Information Network Embedding
- Ubuntu wireless network connection in command line
- LINE:Large-Information Network Embedding
- CSU-ACM2017暑期训练5-三分 E - Line belt HDU - 3400
- CSU 1412 Line and Circles
- Assume the coasting is an infinite straight line. Land is in one side of coasting, sea in the other.
- Telephone and Network, transport on one Cat-5 cable.
- USING THE NETWORKMANAGER COMMAND LINE TOOL, NMCLI
- CSU---D: Simple Line Editor
- PSTN(Public Switched Telephone Network, 公共交换电话网络)简介