1787: [Ahoi2008]Meet 紧急集合

1787: [Ahoi2008]Meet 紧急集合

Time Limit: 20 Sec  Memory Limit: 162 MB
Submit: 1482  Solved: 652
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Description

Input

Output

Sample Input

6 4
1 2
2 3
2 4
4 5
5 6
4 5 6
6 3 1
2 4 4
6 6 6

Sample Output

5 2
2 5
4 1
6 0

HINT

Source

Day1

题解：很明显，两个人的时候，最优方案即为两者的LCA；而三个点时，必然是某两个点的LCA，然后求出两两的LCA，然后判断即可= =，直接水过

 /**************************************************************
     Problem:
     User: HansBug
     Language: Pascal
     Result: Accepted
     Time: ms
     Memory: kb
 ****************************************************************/

 type
     point=^node;
     node=record
                g:longint;
                next:point;
     end;
 var
    i,j,k,l,m,n,a1,a2,a3,a4,a5,a6:longint;
    a:array[..] of point;
    b:array[..] of longint;
    c:array[..,..] of longint;
    d:array[..,..] of longint;
 function min(x,y:longint):longint;
          begin
               if x<y then min:=x else min:=y;
          end;
 function max(x,y:longint):longint;
          begin
               if x>y then max:=x else max:=y;
          end;
 function max3(x,y,z:longint):longint;
          begin
               exit(max(max(x,y),z));
          end;
 procedure swap(var x,y:longint);
           var z:longint;
           begin
                z:=x;x:=y;y:=z;
           end;
 procedure add(x,y:longint);
           var p:point;
           begin
                new(p);p^.g:=y;p^.next:=a[x];a[x]:=p;
           end;
 procedure dfs(y,x:longint);
           var p:point;
           begin
                p:=a[x];
                while p<>nil do
                      begin
                           if p^.g<>y then
                              begin
                                   b[p^.g]:=b[x]+;
                                   c[,p^.g]:=x;
                                   dfs(x,p^.g);
                              end;
                           p:=p^.next;
                      end;
           end;
 function getfat(x,y:longint):longint;
          var i:longint;
          begin
               i:=;
               while y> do
                     begin
                          if odd(y) then x:=c[i,x];
                          inc(i);y:=y div ;
                     end;
               exit(x);
          end;
 function getcom(x,y:longint):longint;
          var i:longint;
          begin
               if b[x]<b[y] then swap(x,y);
               x:=getfat(x,b[x]-b[y]);
               if x=y then exit(x);
               for i:=trunc(ln(b[x])/ln()+) downto  do
                   if c[i,x]<>c[i,y] then
                      begin
                           x:=c[i,x];
                           y:=c[i,y];
                      end;
               exit(c[,x]);
          end;
 function dis(x,y:longint):longint;
          var z:longint;
          begin
               z:=getcom(x,y);
               exit(b[x]-b[z]+b[y]-b[z]);
          end;
 procedure sort(l,r:longint);
           var i,j,x,y:longint;
           begin
                i:=l;j:=r;x:=d[(l+r) div ,];y:=d[(l+r) div ,];
                repeat
                      while (d[i,]<x) do inc(i);
                      while (d[j,]>x) do dec(j);
                      if i<=j then
                         begin
                              swap(d[i,],d[j,]);
                              swap(d[i,],d[j,]);
                              inc(i);dec(j);
                         end;
                until i>j;
                if i<r then sort(i,r);
                if l>j then sort(l,j);
           end;
 begin
      readln(n,m);
      for i:= to n do a[i]:=nil;
      for i:= to n- do
          begin
               readln(j,k);
               add(j,k);add(k,j);
          end;
      l:=random(n)+;b[l]:=;
      dfs(,l);
      for i:= to trunc(ln(n)/ln()+) do
          for j:= to n do
              c[i,j]:=c[i-,c[i-,j]];
      for i:= to m do
          begin
               readln(j,k,l);
               a1:=getcom(j,k);
               a2:=getcom(k,l);
               a3:=getcom(j,l);
               a4:=dis(a1,l);
               d[,]:=(b[j]-b[a1])+(b[k]-b[a1])+a4;
               d[,]:=a1;
               a5:=dis(a2,j);
               d[,]:=a5+(b[k]-b[a2])+(b[l]-b[a2]);
               d[,]:=a2;
               a6:=dis(a3,k);
               d[,]:=(b[j]-b[a3])+a6+(b[l]-b[a3]);
               d[,]:=a3;
               sort(,);writeln(d[,],' ',d[,]);
          end;
 end.