SPOJ913. Query on a tree II

题目大意：

询问一棵树上两点之间的边权和or第k个点是多少

link-cut tree

一开始把第k个点看成了第k大的边……吓了我一跳……

边权处理方法类似QTREE，再维护一个sum一个size就行了……

犯了脑残错误……调了半小时……

//Lib #include<cstdio> #include<cstring> #include<cstdlib> #include<cmath> #include<ctime> #include<iostream> #include<algorithm> #include<vector> #include<string> #include<queue> using namespace std; //Macro #define rep(i,a,b) for(int i=a,tt=b;i<=tt;++i) #define rrep(i,a,b) for(int i=a,tt=b;i>=tt;--i) #define erep(i,e,x) for(int i=x;i;i=e[i].next) #define irep(i,x) for(__typedef(x.begin()) i=x.begin();i!=x.end();i++) #define read() (strtol(ipos,&ipos,10)) #define sqr(x) ((x)*(x)) #define pb push_back #define PS system("pause"); typedef long long ll; typedef pair<int,int> pii; const int oo=~0U>>1; const double inf=1e20; const double eps=1e-6; string name="",in=".in",out=".out"; //Var struct T { int LC,RC,FA,SIZE,KEY,SUM; void set(){LC=RC=FA=SIZE=KEY=SUM=0;} #define lc(x) tree[x].LC #define rc(x) tree[x].RC #define fa(x) tree[x].FA #define size(x) tree[x].SIZE #define key(x) tree[x].KEY #define sum(x) tree[x].SUM }tree[10008]; struct E { int node,next,v; }e[20008]; int n,m,T; int h[10008],tot; void add(int a,int b,int c){e[++tot].next=h[a];e[tot].node=b;e[tot].v=c;h[a]=tot;} void DFS(int x,int fa) { int y; erep(i,e,h[x])if((y=e[i].node)!=fa) { key(y)=e[i].v;fa(y)=x;DFS(y,x); } } void Update(int x) { sum(x)=sum(lc(x))+sum(rc(x))+key(x); size(x)=size(lc(x))+size(rc(x))+1; } void Zig(int x) { int y=fa(x),z=fa(y); if(lc(z)==y)lc(z)=x;else if(rc(z)==y)rc(z)=x;fa(x)=z; fa(rc(x))=y;lc(y)=rc(x);rc(x)=y;fa(y)=x; Update(y); } void Zag(int x) { int y=fa(x),z=fa(y); if(lc(z)==y)lc(z)=x;else if(rc(z)==y)rc(z)=x;fa(x)=z; fa(lc(x))=y;rc(y)=lc(x);lc(x)=y;fa(y)=x; Update(y); } bool isRoot(int x){return lc(fa(x))!=x&&rc(fa(x))!=x;} void Splay(int x) { for(int y,z;!isRoot(x);) { y=fa(x);z=fa(y); if(isRoot(y)) if(lc(y)==x)Zig(x); else Zag(x); else if(lc(z)==y) if(lc(y)==x)Zig(y),Zig(x); else Zag(x),Zig(x); else if(rc(y)==x)Zag(y),Zag(x); else Zig(x),Zag(x); } Update(x); } void Expose(int x){for(int y=0;x;x=fa(x)){Splay(x);rc(x)=y;Update(x);y=x;}} int Find(int root,int k) { while(1) { if(size(lc(root))+1==k)return root; if(size(lc(root))>=k)root=lc(root); else{k-=size(lc(root))+1;root=rc(root);} } } int Query(int x,int y,int z=0) { Expose(y); for(y=0;x;x=fa(x)) { Splay(x);if(!fa(x))break;rc(x)=y;Update(x);y=x; } if(z==0)return sum(rc(x))+sum(y); if(size(y)>=z)return Find(y,size(y)-z+1); else if(size(y)+1==z)return x; else {z-=size(y)+1;return Find(rc(x),z);} } void Init() { scanf("%d",&n);int a,b,c; rep(i,1,n)h[i]=0,tree[i].set();tot=1; rep(i,1,n-1) { scanf("%d%d%d",&a,&b,&c); add(a,b,c),add(b,a,c); } DFS(1,0); } void Work() { int a,b,c;char ch[10]; while(1) { scanf("%s",ch); if(ch[1]=='O')return; scanf("%d%d",&a,&b); if(ch[1]=='I')printf("%d\n",Query(a,b)); else scanf("%d",&c),printf("%d\n",Query(a,b,c)); } } int main() { // freopen((name+in).c_str(),"r",stdin); // freopen((name+out).c_str(),"w",stdout); for(scanf("%d",&T);T;T--) { Init(); Work(); } return 0; }