Codeforces 1051E. Vasya and Big Integers

#include<bits/stdc++.h>
#define ll long long
#define pb push_back
#define ls x<<1
#define rs x<<1|1
#define ull unsigned long long
#define _mp make_pair
#define ldb long double
using namespace std;
const int maxn=1e5+100;
const ll inf=1e18;
int bcg[maxn];
struct Edge
{
    int u,v,nxt;
    ll w;
}edge[maxn*2],edge1[maxn*2];
vector<Edge>vec[maxn];
struct Node{
    ll p;
    int v;
    friend bool operator<(Node a,Node b)
    {
        return a.p>b.p;
    }
    Node(){}
    Node(ll x,int y){p=x,v=y;}
};
int head[maxn],head1[maxn];
ll deep[maxn];
int depth[maxn];
int bian[maxn*2];
ll dis[50][maxn];
int lca[maxn][25];
int vis[maxn];
int cnt,cnt1,tot;
int n,m;
int findd(int x)
{
    return bcg[x]==x?bcg[x]:bcg[x]=findd(bcg[x]);
}
bool cmp(Edge a,Edge b)
{
    return a.w<b.w;
}
void add_e1(int x,int y,ll w)
{
    ++cnt1;edge1[cnt1].u=x;edge1[cnt1].v=y;edge1[cnt1].w=w;edge1[cnt1].nxt=head1[x];head1[x]=cnt1;
}
void add_e(int x,int y,ll w)
{
    ++cnt;edge[cnt].u=x;edge[cnt].v=y;edge[cnt].w=w;edge[cnt].nxt=head[x];head[x]=cnt;
}
int merges(int x,int y)
{
    int xx=findd(x);
    int yy=findd(y);
    if(xx!=yy)
    {
        bcg[xx]=yy;
        return 1;
    }
    return 0;
}
void init()
{
    cnt=cnt1=0;
    tot=0;
    memset(deep,0,sizeof(deep));
    memset(head,0,sizeof(head));
    memset(head1,0,sizeof(head1));
}
void dfs(int x,int ff)
{
    lca[x][0]=ff;
    for(int i=1;i<=20;i++)lca[x][i]=lca[lca[x][i-1]][i-1];
    for(int i=head[x];i;i=edge[i].nxt)
    {
        int v=edge[i].v;
        if(v==ff)continue;
        deep[v]=deep[x]+edge[i].w;
        depth[v]=depth[x]+1;
        dfs(v,x);
    }
}
int LCA(int x,int y)
{
    if(depth[x]<depth[y])swap(x,y);
    int ff=depth[x]-depth[y];
    for(int i=20;i>=0;i--)
    {
        if(ff&(1<<i))x=lca[x][i];
    }
    if(x==y)return y;
    for(int i=20;i>=0;i--)
    {
        if(lca[x][i]!=lca[y][i])x=lca[x][i],y=lca[y][i];
    }
    return lca[y][0];
}
priority_queue<Node>que;
void dij(int id,int x)
{
    for(int i=0;i<=n+4;i++)
    {
        dis[id][i]=inf;
        vis[i]=0;
    }
    dis[id][x]=0;
    while(!que.empty())que.pop();
    que.push(Node(0,x));
    while(!que.empty())
    {
        Node vv=que.top();que.pop();
        if(vis[vv.v]||vv.p>dis[id][vv.v])continue;
        vis[vv.v]=1;
        for(int i=0;i<(int)vec[vv.v].size();i++)
        {
            Edge k=vec[vv.v][i];
            int sw=k.v;
            if(vis[sw])continue;
            if(dis[id][sw]>dis[id][vv.v]+k.w)
            {
                dis[id][sw]=dis[id][vv.v]+k.w;
                que.push(Node(dis[id][sw],sw));
            }
        }

    }
}
int main()
{
    scanf("%d%d",&n,&m);
    int u,v;
    ll w;
    init();
    for(int i=1;i<=m;i++)
    {
        scanf("%d%d%lld",&u,&v,&w);
        add_e1(u,v,w);
        vec[u].push_back((Edge){u,v,0,w});
        vec[v].push_back((Edge){v,u,0,w});
    }
    sort(edge1+1,edge1+cnt1+1,cmp);
    for(int i=1;i<=n+4;i++)bcg[i]=i;
    for(int i=1;i<=cnt1;i++)
    {
        int x=edge1[i].u,y=edge1[i].v;
        if(merges(x,y))
        {
            add_e(x,y,edge1[i].w);
            add_e(y,x,edge1[i].w);
        }
        else
        {
            bian[++tot]=x;
            bian[++tot]=y;
        }
    }
    depth[1]=0;
    deep[1]=0;
    dfs(1,0);
    sort(bian+1,bian+1+tot);
    int sz=unique(bian+1,bian+1+tot)-(bian+1);
    for(int i=1;i<=sz;i++)
    {
        dij(i,bian[i]);
    }
    int q;
    scanf("%d",&q);
    int x,y;
    while(q--)
    {
        scanf("%d%d",&x,&y);
        ll ans=inf;
        int pq=LCA(x,y);

        ans=deep[x]+deep[y]-2*deep[pq];
        for(int i=1;i<=sz;i++)
        {
            ans=min(ans,dis[i][x]+dis[i][y]);
        }
        cout<<ans<<"\n";
    }
    return 0;
}