and check Set

Title: http://acm.hdu.edu.cn/showproblem.php?pid=1598

Https://zh.wikipedia.org/wiki/%E5%B9%B6%E6%9F%A5%E9%9B%86

Http://www.cnblogs.com/nanke/archive/2012/02/13/2350008.html

Think and find a way to use

For the road in question, sort by speed, so that if all the roads from route I to J are able to connect I and J, then there is a way, and the comfort of the road is the difference between the two. This way, as long as the enumeration starts at each road and finds the comfort of the road where the starting and ending points can be connected, you can find the answer.

Code:

1#include <iostream>2#include <algorithm>3 using namespacestd;4 structEdge5 {6     intu,v,w;7}e[1001];8 intf[201],n,m;9 BOOLcmp (Edge A,edge B)Ten { One     returna.w<B.W; A } - voidInit () - { the      for(intI=0; i<=n;i++) -f[i]=i; - } - intFindintx) + { -     if(x==F[x]) +         returnF[x]; Af[x]=find (F[x]); at     returnF[x]; - } - voidUnion (intXinty) - { -     intA=find (x); -     intb=find (y); in     if(a==b) -         return;  tof[a]=b; + } - intMain () the { *     intQ; $      while(SCANF ("%d%d", &n,&m) = =2)Panax Notoginseng     { -          for(intI=0; i<m;i++) thescanf" %d%d%d",&e[i].u,&e[i].v,&E[I].W); +Sort (e,e+m,cmp); Ascanf"%d",&Q); the          while(q--) +         {     -             intx, y; $             intans=Int_max; $scanf"%d%d",&x,&y); -              for(intI=0; i<m;i++) -             { the init (); -                 intflag=0, k=0;Wuyi                  for(intj=i;j<m;j++) the                 { -                 //cout<<e[j].u<< ' <<e[j].v<<endl; Wu Union (E[J].U,E[J].V); -                     if(Find (x) = =find (y)) About                     { $flag=1; -k=J; -                          Break; -                     } A                 //cout<<find (x) << ' <<find (y) <<endl; +                 } the                 if(!flag) Break; -Ans=min (ans,e[k].w-E[I].W); $             } the             if(ans==Int_max) theprintf"-1\n"); the             Elseprintf"%d\n", ans); the         } -     }     in     return 0; the}

and check Set