Tree Chain Split

http://blog.sina.com.cn/s/blog_7a1746820100wp67.html This blog is very good, very clear.

http://acm.hust.edu.cn/vjudge/problem/viewProblem.action?id=13013 This is a simple question.

The code is as follows:

#include <queue>#include<stack>#include<cmath>#include<cstdio>#include<cstring>#include<iostream>#include<algorithm>#defineINF 99999999#definell __int64#defineLson l,m,rt<<1#defineRson m+1,r,rt<<1|1using namespacestd;Const intMAXN =10010;structnode{intto ; intv; intNext;} EDGE[MAXN*3];intPre[maxn],ind,top[maxn],fa[maxn],son[maxn],w[maxn],deq[maxn],siz[maxn],fn;inttree[maxn<<2],val[maxn][3],n;voidAddintXintYintz) {edge[ind].to=y; EDGE[IND].V=Z; Edge[ind].next=Pre[x]; PRE[X]= ind++;}//first search find siz[],son[],deq[],fa[]voidDFS1 (intRtintPaintd) {Deq[rt]=D; SON[RT]=0; FA[RT]=PA; SIZ[RT]=1; inti;  for(I=pre[rt]; i!=-1; I=Edge[i].next) {        intt =edge[i].to; if(t! =Fa[rt]) {DFS1 (t,rt,d+1); SIZ[RT]+=Siz[t]; if(Siz[son[rt]] < siz[t]) {//if the parent node's SON[RT] iz[] is less than the child node's siz[] Update son[]SON[RT] =T; }        }    }}//second search find w[],top[]voidDFS2 (intRtintTP) {Top[rt]=TP; W[RT]= ++N; if(Son[rt]! =0) DFS2 (SON[RT],TP);//if the current parent node is pure in Son, then in order to let the chain in the line segment tree to search for son[] consecutively, and the top of the edge of the same point.      for(intI=PRE[RT]; i!=-1; I=Edge[i].next) {        intt =edge[i].to; if(t! = Fa[rt] && son[rt]! =t)        {DFS2 (t,t); }    }}voidUpdata (intPintVintLintRintRT) {    if(L = =R) {Tree[rt]=v; return ; }    intm = (l+r)/2; if(M >=p)    {Updata (P,v,lson); }    Else{updata (P,v,rson); } Tree[rt]= Max (tree[rt<<1],tree[rt<<1|1]);}intQueryintLintRintLintRintRT) {    if(L<=l && r<=s) {        returnTree[rt]; }    intm = (l+r)/2; intAns =0; if(M >=L) {ans=Max (Ans,query (L,r,lson)); }    if(M <R) {ans=Max (Ans,query (L,r,rson)); }    returnans;}intLcaintXinty) {    intF1,f2; intAns =0;  while(Top[x]! =Top[y]) {        if(Deq[top[x]) <Deq[top[y]])        {Swap (x, y); } ans= Max (Ans,query (w[top[x]],w[x),1Fn1)); X=Fa[top[x]]; }    if(x = =y)returnans; if(Deq[x] <Deq[y])    {Swap (x, y); }    returnMax (Ans,query (w[son[y]],w[x),1Fn1))    ;}intMain () {inti,j,t; scanf ("%d",&t);  while(t--) {scanf ("%d",&N); IND=1; memset (PRE,-1,sizeof(pre));  for(i=1; i<n; i++){            intx, Y, Z scanf ("%d%d%d",&x,&y,&z); val[i][0] =x; val[i][1] =y; val[i][2] =Z;            Add (x, y, z);        Add (y,x,z); } memset (Tree,0,sizeof(tree)); DFS1 (1,1,1); FN=0; DFS2 (1,1);  for(i=1; i<n; i++){            if(deq[val[i][0]] > deq[val[i][1]]) {Swap (val[i][0],val[i][1]); } updata (w[val[i][1]],val[i][2],1Fn1); }        Chars[ the];  while(1) {scanf ("%s", s); if(s[0] =='D')                 Break; if(s[0] =='C'){                intx, y; scanf ("%d%d",&x,&y); Updata (w[val[x][1]],y,1Fn1); }            Else {                intx, y; scanf ("%d%d",&x,&y); printf ("%d\n", LCA (x, y)); }        }    }}

Tree Chain Split