hdu 2586

//spfa算法求最短路，邻接表的讲解参考：http://www.cnblogs.com/mengzhong/p/4713421.html

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<cmath>
#include<cctype>
#include<queue>
#include<stack>
#include<vector>
#include<algorithm>

using namespace std;
typedef long long LL;
#define N 100010
#define INF 0x3f3f3f3f

int n, m, head[N], k, dist[N], vis[N], used[N];
struct node
{
    int v, len, next;
} maps[N];

void add(int u, int v, int len)
{
    maps[k].v=v;
    maps[k].len=len;
    maps[k].next=head[u];
    head[u]=k++;
}

int spfa(int a, int b)
{
    memset(vis, 0, sizeof(vis));
    memset(used, 0, sizeof(used));
    for(int i=0; i<=n; i++)
        dist[i]=INF;
    int P;
    queue<int> q;
    q.push(a);
    dist[a]=0;
    used[a]=1;
    vis[a]=1;

    while(q.size())
    {
        P=q.front();
        //vis[P]=0;
        q.pop();
        for(int i=head[P]; i!=-1; i=maps[i].next)
        {
            int v=maps[i].v;
            if(dist[v]>maps[i].len+dist[P])
                dist[v]=maps[i].len+dist[P];
            if(vis[v])
                continue;
            q.push(v);
            vis[v]=1;
            used[v]++;
            if(used[v]>=n)
                ;
        }
    }
    return dist[b];
}

int main()
{
    int T, a, b, c;
    scanf("%d", &T);

    while(T--)
    {
        k=1;
        memset(head, -1, sizeof(head));
        scanf("%d%d", &n, &m);
        for(int i=0; i<n-1; i++)
        {
            scanf("%d%d%d", &a, &b, &c);
            add(a, b, c);
            add(b, a, c);
        }
        while(m--)
        {
            scanf("%d%d", &a, &b);
            int ans=spfa(a, b);
            printf("%d
", ans);
        }
    }
    return 0;
}