bzoj1103 POI2007 Metropolitan Meg

See the next NOI water problem and then the first time I yy out of the DFS sequence this thing (of course, before listening to others have not written)

And then do a DFS-ordered water problem.

Practice:

Counts the DFS order of a point, becomes pos[i] and the maximum value of pos[i] in all points with that node as a subtree En[i]

And then modify the interval query processing with a tree-like array single point

You can think of the process of inquiry as a DFS, go to an edge ans++, return ans--, then for a point we add (pos[x],1) Add (en[x]+1,-1) to simulate this process is to remove the effect of the fork, it is possible to add a super-source connected to the number 1th point, So every time it comes through an edge, so query (Pos[i]) is the number of edges passed, but the edge of the super source cannot be calculated, so ans--。

For the modification, an edge will cause all points in his subtree to have an answer of 1, so Add (pos[x],-1) Add (en[x]+1,1)

Bzoj, however, does not have a handwritten stack

#include <iostream>#include<cstring>#include<cstdlib>#include<cstdio>#include<algorithm>using namespacestd;Const intmaxn=250000+Ten;intpos[maxn],en[maxn],clk=0;structedge{intto ; Edge*Next; Edge (intto=0, edge*next=0): To, Next (next) {}}POOL[MAXN*2],*fir[maxn],*pis=Pool;voidAddedge (int  from,intTo ) {    *pis=edge (to,fir[ from]); fir[ from]=pis++; *pis=edge ( from, Fir[to]); fir[to]=pis++;}intFA[MAXN];voidDfsintx) {pos[x]=++CLK;  for(Edge*p=fir[x];p;p=p->next) {        intV=p->to ; if(V==fa[x])Continue; FA[V]=x;    DFS (v); } En[x]=CLK;} intC[maxn],n;voidAddintXintd) { for(;0<x&&x<=n;x+=x&-x) c[x]+=D;}intQueryintx) {intret=0;  for(;0<x&&x<=n;x-=x&-x) ret+=C[x]; returnret;}intMain () {#ifdef DEBUG freopen ("In.txt","R", stdin);//freopen ("OUT.txt", "w", stdout);#endifscanf ("%d",&N);  for(intI=1; i<n;i++) {        intu,v; scanf ("%d%d",&u,&v);    Addedge (U,V); } DFS (1);  for(intI=1; i<=n;i++) {Add (Pos[i],1); Add (En[i]+1,-1); }    intm;  for(SCANF ("%d",&m); m;) {        Charopt; intx, y;  while(Opt=getchar (), opt!='A'&&opt!='W'); if(opt=='A') {scanf ("%d%d",&x,&y); if(fa[y]==×) swap (x, y); Add (Pos[x],-1); Add (En[x]+1,1); }Else{scanf ("%d",&x); printf ("%d\n", query (Pos[x])-1); M--; }    }        return 0;}

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bzoj1103 POI2007 Metropolitan Meg