倍增水题……
本来还想用LCT做的……然后发现根本不需要
1 //minamoto 2 #include<bits/stdc++.h> 3 using namespace std; 4 #define getc() (p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++) 5 char buf[1<<21],*p1=buf,*p2=buf; 6 inline int read(){ 7 #define num ch-'0' 8 char ch;bool flag=0;int res; 9 while(!isdigit(ch=getc())) 10 (ch=='-')&&(flag=true); 11 for(res=num;isdigit(ch=getc());res=res*10+num); 12 (flag)&&(res=-res); 13 #undef num 14 return res; 15 } 16 inline bool isop(char ch){ 17 return ch=='I'||ch=='H'||ch=='O'; 18 } 19 inline char readop(){ 20 char ch; 21 while(!isop(ch=getc())); 22 return ch; 23 } 24 const int N=10005; 25 int head[N],Next[N<<1],edge[N<<1],ver[N<<1],fa[N][16],d[N],dist[N]; 26 int n,m,tot; 27 inline void add(int u,int v,int e){ 28 ver[++tot]=v,Next[tot]=head[u],head[u]=tot,edge[tot]=e; 29 ver[++tot]=u,Next[tot]=head[v],head[v]=tot,edge[tot]=e; 30 } 31 void dfs(int u,int f){ 32 d[u]=d[f]+1,fa[u][0]=f; 33 for(int i=1;(1<<i)<=d[u];++i) fa[u][i]=fa[fa[u][i-1]][i-1]; 34 for(int i=head[u];i;i=Next[i]){ 35 int v=ver[i]; 36 if(v==f) continue; 37 dist[v]=dist[u]+edge[i],dfs(v,u); 38 } 39 } 40 int LCA(int x,int y){ 41 if(d[x]<d[y]) swap(x,y); 42 for(int i=15;i>=0;--i) 43 if(d[fa[x][i]]>=d[y]) x=fa[x][i]; 44 if(x==y) return x; 45 for(int i=15;i>=0;--i) 46 if(fa[x][i]!=fa[y][i]) 47 x=fa[x][i],y=fa[y][i]; 48 return fa[x][0]; 49 } 50 int querylen(int x,int y,int k){ 51 int lca=LCA(x,y); 52 if(d[x]-d[lca]+1>=k){ 53 int ans=d[x]-k+1; 54 for(int i=15;i>=0;--i) 55 if((1<<i)<=d[x]-ans) x=fa[x][i]; 56 return x; 57 } 58 else{ 59 int ans=d[lca]*2+k-d[x]-1; 60 for(int i=15;i>=0;--i){ 61 if(d[y]-(1<<i)>=ans) y=fa[y][i]; 62 } 63 return y; 64 } 65 } 66 int main(){ 67 //freopen("testdata.in","r",stdin); 68 int q=read(); 69 while(q--){ 70 memset(head,0,sizeof(head)); 71 memset(fa,0,sizeof(fa)); 72 d[1]=dist[1]=0,tot=0; 73 int n=read(); 74 for(int i=1;i<n;++i){ 75 int u=read(),v=read(),e=read(); 76 add(u,v,e); 77 } 78 dfs(1,0); 79 bool flag=true; 80 while(flag){ 81 char op=readop(); 82 switch(op){ 83 case 'O':flag=false;break; 84 case 'I':{ 85 int u=read(),v=read(); 86 int lca=LCA(u,v); 87 printf("%d ",dist[u]+dist[v]-2*dist[lca]); 88 break; 89 } 90 case 'H':{ 91 int u=read(),v=read(),k=read(); 92 printf("%d ",querylen(u,v,k)); 93 break; 94 } 95 } 96 } 97 puts(""); 98 } 99 return 0; 100 }