3391: [Usaco2004 dec]tree Cutting Network damage

3391: [Usaco2004 dec]tree cutting Network damage time limit:1 Sec Memory limit:128 MB
submit:76 solved:59
[Submit] [Status] [Discuss] Description John, realizing that Bessie's construction network had cost him a huge amount of money, fired her. Bessie was furious and intended to retaliate.    She intends to destroy the newly built network of John. John's network is tree-shaped, connected to the N (1≤n≤10000) barn. She intends to cut off the power of one of the barns, leaving all the cables connected to the barn completely interrupted. After that, there will be several sub-networks. To ensure that the damage is large enough, each subnet should not be more than half of the number of cattle sheds, which is worth destroying the barn?    Input line 1th: an integer n. 2nd to n+1: Enter two integers per line representing the two endpoints of a cable. Output outputs all the damage-worthy barns in order from small to large. If no one is worth destroying, the output is "NONE". Sample Input10
1 2
2 3
3 4
4 5
6 7
7 8
8 9
9 10
3 8Sample Output3
8

If the Barn 3 or bullpen 8 is destroyed, the remaining three subnet nodes will be 5,2,2, with no more than 5.
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Problem: A tree of water, the key is how to quickly find the size of the sub-tree around the point, in fact, only need DFS preprocessing to a certain point (such as point 1) as the root of the tree each subtree size, and for a certain point, the size of each subtree is in the case of a root tree of its individual subtree size, There is another subtree size that is n-size[x] (size[x) is labeled as the size of the subtree with the root tree in the case of the root, and then simple to determine, the complexity O (N)

1/**************************************************************2Problem:33913 User:hansbug4 language:pascal5 result:accepted6Time: -Ms7Memory:1716KB8****************************************************************/9  Ten type OnePoint=^node; ANode=Record - G:longint; - Next:point; the     End; - var - I,j,k,l,m,n:longint; -A:Array[0..100000] ofPoint ; +B:Array[0..100000] ofLongint; -C:Array[0..100000] ofLongint; + procedureAdd (x,y:longint); A           varP:point; at           begin -New (p);p ^.g:=y;; -p^.next:=a[x];a[x]:=p; -           End; - procedureDFS (y,x:longint); -           varP:point;i:longint; in           begin -p:=a[x];b[x]:=1; i:=1; to                 whileP<>Nil  Do +                      begin -                           ifP^.g<>y Then the                              begin * DFS (X,P^.G); $                                   ifB[p^.g]> (nDiv 2) Theni:=0;Panax Notoginseng Inc (B[X],B[P^.G]); -   the                              End; +p:=P^.next; A                      End; the                if((N-b[x]) <= (nDiv 2)) and(i=1) Then +                   begin -Inc (c[0]); $c[c[0]]:=x; $                   End; -           End; - proceduresort (l,r:longint); the           varI,j,x,y:longint; -           beginWuyii:=l;j:=r;x:=c[(L+r)Div 2]; the                Repeat -                       whileC[i]<x DoInc (i); Wu                       whileC[j]>x DoDec (j); -                      ifI<=j Then About                         begin $y:=c[i];c[i]:=c[j];c[j]:=y; - Inc (I);d EC (j); -                         End; -                untilI>J; A                ifI<r Thensort (i,r); +                ifL<j Thensort (l,j); the           End; - begin $READLN (n); c[0]:=0; the       fori:=1  toN Doa[i]:=Nil; the       fori:=1  toN-1  Do the          begin the readln (j,k); - Add (j,k); add (k,j); in          End; theDfs0,1); Sort (1, c[0]); the       fori:=1  toc[0] DoWriteln (C[i]); About Readln; the End.

3391: [Usaco2004 dec]tree Cutting Network damage