POJ-1986-Distance Queries

#include <iostream>
#include <memory.h>
#include <string>
#include <istream>
#include <sstream>
#include <vector>
#include <stack>
#include <algorithm>
#include <map>
#include <queue>
#include <math.h>
#include <cstdio>
#include <set>
#include <iterator>
#include <cstring>
using namespace std;

typedef long long LL;
const int MAXN = 4e4+10;
struct Node
{
    int from_, to_, dist_;
    Node(int from, int to, int dist):from_(from), to_(to), dist_(dist){}
};
vector<Node> G[MAXN];
vector<Node> Q[MAXN];
int fa[MAXN], dis[MAXN];
int vis[MAXN], fas[MAXN];
int Res[MAXN];
int n, m, l, r, v, k;
int root, res;

int Get_F(int x)
{
    if (fa[x] == x)
        return x;
    fa[x] = Get_F(fa[x]);
    return fa[x];
}

void Merge(int u, int v)
{
    int tv = Get_F(v);
    int tu = Get_F(u);
    if (tv != tu)
        fa[v] = u;
}

void Tarjan(int u)
{
    vis[u] = 1;
    for (int i = 0;i < Q[u].size();i++)
    {
        Node node = Q[u][i];
        if (vis[node.to_] == 1)
        {
            int lenth = dis[node.from_]+dis[node.to_]-2*dis[Get_F(node.to_)];
            Res[node.dist_] = lenth;
        }
    }
    for (int i = 0;i < G[u].size();i++)
    {
        Node node = G[u][i];
        if (!vis[node.to_])
        {
            dis[node.to_] = dis[node.from_] + node.dist_;
            Tarjan(node.to_);
            Merge(node.from_, node.to_);
        }
    }
}

void init()
{
    for (int i = 1;i <= n;i++)
    {
        G[i].clear();
        fa[i] = i;
    }
    memset(vis, 0, sizeof(vis));
    memset(dis, 0, sizeof(vis));
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    int t;
    //cin >> t;
    //while (t--)
    while(~scanf("%d%d", &n, &m))
    {
//        cin >> n >> m;
//        scanf("%d%d", &n, &m);
        char op;
        init();
        for (int i = 1;i <= m;i++)
        {
//            cin >> l >> r >> v >> op;
            scanf("%d%d%d %c", &l, &r, &v, &op);
            G[l].push_back(Node(l, r, v));
            G[r].push_back(Node(r, l, v));
        }
        scanf("%d", &k);
        for (int i = 1;i <= k;i++)
        {
//            cin >> l >> r;
            scanf("%d%d", &l, &r);
            Q[l].push_back(Node(l, r, i));
            Q[r].push_back(Node(r, l, i));
        }
        dis[1] = 0;
        Tarjan(1);
        for (int i = 1;i <= k;i++)
        {
            printf("%d\n", Res[i]);
        }
    }

    return 0;
}