1787: [Ahoi2008]Meet 紧急集合
1787: [Ahoi2008]Meet 紧急集合
Time Limit: 20 Sec Memory Limit: 162 MBSubmit: 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
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
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
1 /************************************************************** 2 Problem: 1787 3 User: HansBug 4 Language: Pascal 5 Result: Accepted 6 Time:5352 ms 7 Memory:113532 kb 8 ****************************************************************/ 9 10 type 11 point=^node; 12 node=record 13 g:longint; 14 next:point; 15 end; 16 var 17 i,j,k,l,m,n,a1,a2,a3,a4,a5,a6:longint; 18 a:array[0..1000000] of point; 19 b:array[0..1000000] of longint; 20 c:array[0..22,0..1000000] of longint; 21 d:array[0..5,1..3] of longint; 22 function min(x,y:longint):longint; 23 begin 24 if x<y then min:=x else min:=y; 25 end; 26 function max(x,y:longint):longint; 27 begin 28 if x>y then max:=x else max:=y; 29 end; 30 function max3(x,y,z:longint):longint; 31 begin 32 exit(max(max(x,y),z)); 33 end; 34 procedure swap(var x,y:longint); 35 var z:longint; 36 begin 37 z:=x;x:=y;y:=z; 38 end; 39 procedure add(x,y:longint); 40 var p:point; 41 begin 42 new(p);p^.g:=y;p^.next:=a[x];a[x]:=p; 43 end; 44 procedure dfs(y,x:longint); 45 var p:point; 46 begin 47 p:=a[x]; 48 while p<>nil do 49 begin 50 if p^.g<>y then 51 begin 52 b[p^.g]:=b[x]+1; 53 c[0,p^.g]:=x; 54 dfs(x,p^.g); 55 end; 56 p:=p^.next; 57 end; 58 end; 59 function getfat(x,y:longint):longint; 60 var i:longint; 61 begin 62 i:=0; 63 while y>0 do 64 begin 65 if odd(y) then x:=c[i,x]; 66 inc(i);y:=y div 2; 67 end; 68 exit(x); 69 end; 70 function getcom(x,y:longint):longint; 71 var i:longint; 72 begin 73 if b[x]<b[y] then swap(x,y); 74 x:=getfat(x,b[x]-b[y]); 75 if x=y then exit(x); 76 for i:=trunc(ln(b[x])/ln(2)+1) downto 0 do 77 if c[i,x]<>c[i,y] then 78 begin 79 x:=c[i,x]; 80 y:=c[i,y]; 81 end; 82 exit(c[0,x]); 83 end; 84 function dis(x,y:longint):longint; 85 var z:longint; 86 begin 87 z:=getcom(x,y); 88 exit(b[x]-b[z]+b[y]-b[z]); 89 end; 90 procedure sort(l,r:longint); 91 var i,j,x,y:longint; 92 begin 93 i:=l;j:=r;x:=d[(l+r) div 2,1];y:=d[(l+r) div 2,2]; 94 repeat 95 while (d[i,1]<x) do inc(i); 96 while (d[j,1]>x) do dec(j); 97 if i<=j then 98 begin 99 swap(d[i,1],d[j,1]); 100 swap(d[i,2],d[j,2]); 101 inc(i);dec(j); 102 end; 103 until i>j; 104 if i<r then sort(i,r); 105 if l>j then sort(l,j); 106 end; 107 begin 108 readln(n,m); 109 for i:=1 to n do a[i]:=nil; 110 for i:=1 to n-1 do 111 begin 112 readln(j,k); 113 add(j,k);add(k,j); 114 end; 115 l:=random(n)+1;b[l]:=1; 116 dfs(0,l); 117 for i:=1 to trunc(ln(n)/ln(2)+1) do 118 for j:=1 to n do 119 c[i,j]:=c[i-1,c[i-1,j]]; 120 for i:=1 to m do 121 begin 122 readln(j,k,l); 123 a1:=getcom(j,k); 124 a2:=getcom(k,l); 125 a3:=getcom(j,l); 126 a4:=dis(a1,l); 127 d[1,1]:=(b[j]-b[a1])+(b[k]-b[a1])+a4; 128 d[1,2]:=a1; 129 a5:=dis(a2,j); 130 d[2,1]:=a5+(b[k]-b[a2])+(b[l]-b[a2]); 131 d[2,2]:=a2; 132 a6:=dis(a3,k); 133 d[3,1]:=(b[j]-b[a3])+a6+(b[l]-b[a3]); 134 d[3,2]:=a3; 135 sort(1,3);writeln(d[1,2],' ',d[1,1]); 136 end; 137 end.
