1 #include <cstdio>
  2 #include <iostream>
  3 #include <algorithm>
  4 #include <cstring>
  5 #include <vector>
  6 #define INF 0x3f3f3f3f
  7 #define LL long long
  8 const int MAX_N = 4e4+5;
  9 using namespace std;
 10 
 11 struct Edge{int v, nxt, w;}edge[MAX_N<<1];              //静态邻接表
 12 struct Query
 13 {
 14     int v, id;
 15     Query(){};
 16     Query(int _v, int _id):v(_v), id(_id){};
 17 };
 18 
 19 vector<Query> q[MAX_N];       // !!!                    //查询关系动态二维矩阵
 20 
 21 int head[MAX_N], cnt;                                   //静态邻接表头节点，边数
 22 int dis[MAX_N];                                         //各结点到根结点的距离
 23 int fa[MAX_N];                                          //并查集 祖先数组
 24 bool vis[MAX_N], in[MAX_N];                             //深搜用，找根结点用
 25 int ans[MAX_N];                // !!!                   //各查询答案
 26 int N, M;                                               //结点数，查询数
 27 
 28 void init()
 29 {
 30     memset(head, -1, sizeof(head));                     //初始化
 31     memset(vis, false, sizeof(vis));
 32     memset(in, false, sizeof(in));
 33     memset(dis, 0, sizeof(dis));
 34     memset(ans, 0, sizeof(ans));
 35     cnt = 0;
 36 }
 37 
 38 void AddEdge(int from, int to, int weight)              //静态邻接表加边操作
 39 {
 40     edge[cnt].v = to;
 41     edge[cnt].w = weight;
 42     edge[cnt].nxt = head[from];
 43     head[from] = cnt++;
 44 }
 45 
 46 int getfa(int x)                                        //找祖先
 47 {
 48     int root = x;
 49     while(fa[root] != root) root = fa[root];
 50 
 51     int tmp;
 52     while(fa[x] != root){
 53         tmp = fa[x];
 54         fa[x] = root;
 55         x = tmp;
 56     }
 57     return root;
 58 }
 59 
 60 void dfs(int s)                                         //预处理各根结点到祖先的距离
 61 {
 62     int rt = s;
 63     for(int i = head[s]; i != -1; i = edge[i].nxt){
 64         dis[edge[i].v] = dis[rt] + edge[i].w;
 65         dfs(edge[i].v);
 66     }
 67 }
 68 
 69 void Tarjan(int s)                                      // LCA
 70 {
 71     int root = s;
 72     fa[s] = s;
 73     for(int i = head[s]; i != -1; i = edge[i].nxt){
 74         int Eiv = edge[i].v;
 75         Tarjan(Eiv);
 76         fa[getfa(Eiv)] = s;
 77     }
 78     vis[s] = true;
 79     for(int i = 0; i < q[s].size(); i++){
 80         if(vis[q[s][i].v] && !ans[q[s][i].id]){
 81             ans[q[s][i].id] = dis[q[s][i].v] + dis[s] - 2*dis[getfa(q[s][i].v)];
 82         }
 83     }
 84 }
 85 
 86 int main()
 87 {
 88      int T_case;
 89      scanf("%d", &T_case);
 90      while(T_case--){
 91         init();
 92         scanf("%d %d", &N, &M);
 93         for(int i = 1, u, v, w; i < N; i++){                //建树
 94             scanf("%d %d %d", &u, &v, &w);
 95             AddEdge(u, v, w);
 96             in[v] = true;
 97         }
 98 
 99         for(int i = 1, u, v; i <= M; i++){                  //储存查询信息（离线）
100             scanf("%d %d", &u, &v);
101             q[u].push_back(Query(v, i));
102             q[v].push_back(Query(u, i));
103         }
104 
105         int root = 0;
106         for(int i = 1; i <= N; i++) if(!in[i]){root = i; break;}    //找树根结点
107 
108         dfs(root);              //预处理
109         Tarjan(root);           //LCA
110 
111         for(int i = 1; i <= M; i++){
112             printf("%d\n", ans[i]);
113         }
114         //puts("");
115      }
116      return 0;
117 }