hdu4253 dichotomy +mst (classic model)

N points, M edge, the edge is divided into a, b two classes, to construct a minimum spanning tree, and the number of a side of the tree is K.

We can control the number of a edges in the tree by adding a weight dx to all a edges. Obviously, when the DX increases, the A-side number KK will decrease.

Two-minute DX,

When kk>=k, increase the DX (i.e. l=mid+1) while updating the Ans=sum (MST)-mid*k;

When kk<k, reduce DX (i.e. r=mid-1).

1#include <cstdio>2#include <cstring>3#include <algorithm>4 using namespacestd;5 structnode6 {7     intu,v,w;8}ey[110000],el[110000];9 intn,m,k,numey,numel,sset[110000],sum;Ten Const intmmax=1<< -; One intFfind (intx) A { -     if(sset[x]==x)returnx; -     intFa=Sset[x]; thesset[x]=Ffind (FA); -     returnSset[x]; - } - voidMmerge (intAintb) + { -     intAa=Ffind (a); +     intbb=Ffind (b); A     if(aa!=BB) atsset[aa]=BB; - } - BOOLCMP (node X1,node y1) - { -     returnx1.w<Y1.W; - } in intKruscal (intDX) - { to     inti; +sum=0; -      for(i=0; i<=n;i++) thesset[i]=i; *     intkk=0, posey=0, posel=0, num=0; $      while(posey<numey| | posel<Numel)Panax Notoginseng     { -         int  from, to; the         if(ey[posey].w+dx<=EL[POSEL].W) +         { A              from=Ffind (ey[posey].u); theto=Ffind (EY[POSEY].V); +             if( from!=to ) -             { $ Mmerge (EY[POSEY].U,EY[POSEY].V); $sum+= (ey[posey].w+dx); -kk++; -num++; the             } -posey++;Wuyi         } the         Else -         { Wu              from=Ffind (el[posel].u); -to=Ffind (EL[POSEL].V); About             if( from!=to ) $             { - Mmerge (EL[POSEL].U,EL[POSEL].V); -sum+=EL[POSEL].W; -num++; A             } +posel++; the         } -         if(num==n-1) Break; $     } the     if(kk>=k)return 1; the     Else return 0; the } the intMain () - { in     inti,casnum=0; the      while(SCANF ("%d%d%d", &n,&m,&k)! =EOF) the     { AboutNumey=numel=0; the          for(i=0; i<m;i++) the         { the             inta,b,c,tmp; +scanf"%d%d%d%d",&a,&b,&c,&tmp); -             if(tmp==0) the             {Bayiey[numey].u=A; theey[numey].v=b; theey[numey++].w=C; -             } -             Else the             { theel[numel].u=A; theel[numel].v=b; theel[numel++].w=C; -             } the         } theSort (ey,ey+numey,cmp); theSort (el,el+numel,cmp);94ey[numey].w=el[numel].w=Mmax; the         intl=- -, r= -, mid,ans=0; the          while(l<=R) the         {98Mid= (L+R)/2; About             if(Kruscal (mid)) -             {101L=mid+1;102ans=sum-mid*K;103             }104             Elser=mid-1; the         }106printf"Case %d:%d\n",++Casnum,ans);107     }108     return 0;109}

hdu4253 dichotomy +mst (classic model)