I - I HDU - 2586 (Summer Individual - 17)(BFS)

I - I

 HDU - 2586 
#include<bits/stdc++.h>
using namespace std;
const int maxn=40005;
long long ans;
vector<pair<int,int > >mmp[maxn];
bool vis[maxn];
struct node
{
    int x;
    long long step;
} temp1,temp2;
void bfs(int xx,int yy)
{
    queue<node>q;
    temp1.x=xx;
    temp1.step=0;
    q.push(temp1);
    vis[temp1.x]=1;
    while(!q.empty())
    {
        temp1.x=q.front().x;
        temp1.step=q.front().step;
        q.pop();
        if(temp1.x==yy)
        {
            ans=temp1.step;
            return;
        }
        for(int i=0; i<mmp[temp1.x].size(); i++)
        {
            temp2.x=mmp[temp1.x][i].first;
            temp2.step=temp1.step+mmp[temp1.x][i].second;
            if(!vis[temp2.x])
            {
                q.push(temp2);
                vis[temp2.x]=1;
            }
        }
    }
}
int main()
{
    int t,n,m;
    cin>>t;
    while(t--)
    {
        int u,v,w;
        cin>>n>>m;
        for(int i=1; i<n; i++)
        {
            cin>>u>>v>>w;
            mmp[u].push_back(make_pair(v,w));
            mmp[v].push_back(make_pair(u,w));
        }
        while(m--)
        {
            memset(vis,0,sizeof(vis));
            cin>>u>>v;
            bfs(u,v);
            cout<<ans<<endl;
        }
        for(int i=1; i<=n; i++)
            mmp[i].clear();
    }
    return 0;
}