Bzoj3732:network (minimum spanning tree +lca)

3732:network

Title: Portal

Exercises

At first glance, the largest edge is the smallest, and the direct wave is the smallest spanning tree.

At first, I was afraid it would be wrong to ask a wave of meat, any two points the maximum path on the minimum spanning tree must be minimal.

Then things are going to be easier. Hey, build a tree, direct online LCA, with a mx[i][j] record the maximum value of this interval for the 2^j.

Code:

1#include <cstdio>2#include <cstring>3#include <cstdlib>4#include <cmath>5#include <algorithm>6 using namespacestd;7 structnode8 {9     intx,y,c;Ten}a[111000];intLen; One voidInsintXintYintc) A { -Len++;a[len].x=x;a[len].y=y;a[len].c=C; - } the structEdge - { -     intX,y,c,next; -}e[111000];intllen,last[15100]; + voidInssintXintYintc) - { +Llen++;e[llen].x=x;e[llen].y=y;e[llen].c=C; Ae[llen].next=last[x];last[x]=Llen; at } - inteax15100]; - intFINDFA (intx) {if(fa[x]!=x) Fa[x]=findfa (fa[x]);returnfa[x];} - BOOLCMP (node N1,node n2) {returnn1.c<n2.c;} - intn,m,t; - intbin[ +],dep[15100],f[15100][ +]; in intmx[15100][ +];//record the maximum edge value of a i~i+2^j - voidPre_tree_node (intx) to { +      for(intI=1; i<= -&& dep[x]>=bin[i];i++) -f[x][i]=f[f[x][i-1]][i-1],mx[x][i]=max (mx[x][i-1],mx[f[x][i-1]][i-1]); the      for(intk=last[x];k;k=e[k].next) *     { $         inty=e[k].y;Panax Notoginseng         if(y!=f[x][0]) -         { thedep[y]=dep[x]+1; +f[y][0]=x;mx[y][0]=e[k].c; A Pre_tree_node (y); the         } +     } - } $ intSolintXinty) $ { -     intmaxx=0; -     if(dep[x]<Dep[y]) swap (x, y); the      for(intI= -; i>=0; i--) -         if(dep[x]-dep[y]>=Bin[i])WuyiMaxx=max (Maxx,mx[x][i]), x=F[x][i]; the     if(x==y)returnMaxx; -      for(intI= -; i>=0; i--) Wu         if(Dep[x]>=bin[i] && f[x][i]!=F[y][i]) -Maxx=max (Maxx,max (mx[x][i],mx[y][i)), x=f[x][i],y=F[y][i]; AboutMaxx=max (Maxx,max (mx[x][0],mx[y][0])); $     returnMaxx; - } - intMain () - { Abin[0]=1; for(intI=1; i<= -; i++) bin[i]=bin[i-1]<<1; +scanf"%d%d%d",&n,&m,&T); thellen=len=0; Memset (Last,0,sizeof(last)); -      for(intI=1; i<=m;i++) $     { the         intX,Y,C;SCANF ("%d%d%d",&x,&y,&c); the ins (x,y,c); ins (y,x,c); the     } theSort (A +1, a+len+1, CMP); -      for(intI=1; i<=n;i++) fa[i]=i;inttt=0; in      for(intI=1; i<=len;i++) the     { the         intFX=FINDFA (a[i].x), fy=Findfa (A[I].Y); About         if(fx!=fy) the         { thefa[fy]=fx,tt++; the INSS (A[I].X,A[I].Y,A[I].C); + INSS (A[I].Y,A[I].X,A[I].C); -             if(tt==n-1) Break; the         }Bayi     } the      for(intI=1; i<=n;i++) the         if(fa[i]==i) -f[i][0]=0, dep[i]=1, Pre_tree_node (i); -      while(t--) the     { the         intST,ED;SCANF ("%d%d",&st,&ed); theprintf"%d\n", Sol (st,ed)); the     } -     return 0; the}

Bzoj3732:network (minimum spanning tree +lca)