There are n houses in the village and some bidirectional roads connecting them. Every day peole always like to ask like this "How far is it if I want to go from house A to house B"? Usually it hard to answer. But luckily int this village the answer is always unique, since the roads are built in the way that there is a unique simple path("simple" means you can't visit a place twice) between every two houses. Yout task is to answer all these curious people.
InputFirst line is a single integer T(T<=10), indicating the number of test cases.
For each test case,in the first line there are two numbers n(2<=n<=40000) and m (1<=m<=200),the number of houses and the number of queries. The following n-1 lines each consisting three numbers i,j,k, separated bu a single space, meaning that there is a road connecting house i and house j,with length k(0<k<=40000).The houses are labeled from 1 to n.
Next m lines each has distinct integers i and j, you areato answer the distance between house i and house j.OutputFor each test case,output m lines. Each line represents the answer of the query. Output a bland line after each test case.Sample Input
2
3 2
1 2 10
3 1 15
1 2
2 3
2 2
1 2 100
1 2
2 1
Sample Output
10
25
100
100
1 #include<iostream>
2 #include<stdio.h>
3 #include<vector>
4 #include<algorithm>
5 #include<string.h>
6 using namespace std;
7 int ans[250],vis[40500];
8 vector< pair <int ,int > > vec[40500];
9 vector <pair <int ,int > > query[40500];
10 struct Node{
11 int f;
12 int len;
13 } pre[40500];
14 Node Find(int x)
15 {
16 if(pre[x].f==x)
17 {
18 return pre[x];
19 }
20 else
21 {
22 Node now;
23 now=Find(pre[x].f);
24 pre[x].len+=now.len;
25 pre[x].f=now.f;
26 return pre[x];
27 }
28 }
29 int dfs(int u,int fa,int length)
30 {
31 pre[u].f=u;
32 pre[u].len=0;
33 vis[u]=1;
34 for(int i=0;i<vec[u].size();i++)
35 {
36 int v=vec[u][i].first;
37 int len=vec[u][i].second;
38 if(v==fa) continue;
39 dfs(v,u,len);
40 }
41 for(int i=0;i<query[u].size();i++)
42 {
43 int v=query[u][i].first;
44 int id=query[u][i].second;
45 if(vis[v]==1)
46 {
47 ans[id]=Find(v).len+Find(u).len;
48 }
49 }
50 pre[u].f=fa;
51 pre[u].len+=length;
52 }
53 int main()
54 {
55 int T;
56 cin>>T;
57 while(T--)
58 {
59 int n,q,x,y,k;
60 cin>>n>>q;
61 for(int i=0;i<n-1;i++)
62 {
63 cin>>x>>y>>k;
64 vec[x].push_back({y,k});
65 vec[y].push_back({x,k});
66 vis[y]=1;
67 }
68 for(int i=0;i<q;i++)
69 {
70 cin>>x>>y;
71 query[x].push_back({y,i});
72 query[y].push_back({x,i});
73 }
74 for(int i=1;i<=n;i++)
75 {
76 if(vis[i]==0)
77 {
78 dfs(i,i,0);
79 break;
80 }
81 }
82 for(int i=0;i<q;i++)
83 cout<<ans[i]<<endl;
84 for(int i=0;i<=n;i++)
85 {
86 vec[i].clear();
87 query[i].clear();
88 }
89 memset(pre,0,sizeof(pre));
90 memset(vis,0,sizeof(vis));
91 }
92 return 0;
93 }
