Poj1861 network MST

Source: Internet
Author: User
Tags integer numbers
The longest side of the Spanning Tree requested by kruscal is as small as possible, which is different from Prim's network.

Time limit:1000 ms

 

Memory limit:30000 K

Total submissions:10476

 

Accepted:3945

 

Special Judge

Description

Andrew is working as system administrator and is planning to establish a new network in his company. there will be n hubs in the company, they can be connected to each other using cables. since each worker of the company must have
Access to the whole network, each hub must be accessible by cables from any other hub (with possibly some intermediate hubs ).
Since cables of different types are available and shorter ones are cheaper, it is necessary to make such a plan of Hub Connection, that the maximum length of a single cable is minimal. there is another problem-not each hub can be connected to any other one
Because of compatibility problems and building geometry limitations. Of course, Andrew will provide you all necessary information about possible hub connections.
You are to help Andrew to find the way to Connect hubs so that all above conditions are satisfied.

Input

The first line of the input contains two integer numbers: N-the number of hubs in the network (2 <=n <= 1000) and M-the number of possible hub connections (1 <= m <= 15000 ). all hubs are numbered from 1 to n. the following
M lines contain information about possible connections-the numbers of two hubs, which can be connected and the cable length required to connect them. length is a positive integer number that does not exceed 10 6 .
There will be no more than one way to connect two hubs. A hub cannot be connected to itself. There will always be at least one way to connect all hubs.

Output

Output first the maximum length of a single cable in your Hub Connection plan (the value you should minimize ). then output your plan: first output p-the number of cables used, then output p pairs of integer numbers-Numbers
Of hubs connected by the corresponding cable. Separate numbers by spaces and/or line breaks.

Sample Input

 
4 61 2 11 3 11 4 22 3 13 4 12 4 1

Sample output

 
141 21 32 33 4
 
 
# Include <iostream> # include <vector> # include <cstdio> # include <cstring> # include <algorithm> # include <queue> # include <cmath> # include <iomanip> # include <complex> using namespace STD; # define maxn 1100 struct line {int P1, P2; int dis ;}; line L [maxn * 20], que [maxn]; int N, set [maxn], M; int maxs, num; bool CMP (line A, line B) {return. dis <B. DIS;} void Init (int n) {for (INT I = 0; I <= N; I ++) set [I] = I ;} // search for the set number of A: int find (int A) {int Root = A; int temp; while (set [root]! = Root) root = set [root]; while (set [a]! = Root) {temp = A; A = set [a]; set [temp] = root;} return root;} // merge two sets bool Merge (int, int B) {int x = find (a); int y = find (B); If (x = y) return false; set [x] = y; return true;} void Kruskal () {for (INT I = 0; I <M & num <n-1; I ++) {If (merge (L [I]. p1, L [I]. p2) {Maxs = L [I]. DIS; num ++; que [num]. p1 = L [I]. p1; que [num]. p2 = L [I]. p2 ;}} void solve () {Init (n); For (INT I = 0; I <m; I ++) scanf ("% d", & L [I]. p1, & L [I]. p2, & L [I]. dis); sort (L, L + M, CMP); Maxs = 0, num = 0; Kruskal (); printf ("% d \ n", Maxs ); printf ("% d \ n", num); For (INT I = 1; I <= num; I ++) printf ("% d \ n ", que [I]. p1, que [I]. p2);} int main () {While (CIN> N> m) solve (); Return 0 ;}

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.