BNUOJ 2105 Distance Queries

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cstdlib>
 5 #include <vector>
 6 #include <climits>
 7 #include <algorithm>
 8 #include <cmath>
 9 #define LL long long
10 #define INF 0x3f3f3f
11 using namespace std;
12 const int maxn = 100010;
13 struct arc{
14     int to,w;
15 };
16 struct query{
17     int to,id;
18 };
19 int n,m,k,ans[maxn],d[maxn],uf[maxn];
20 bool vis[maxn];
21 vector<arc>g[maxn];
22 vector<query>q[maxn];
23 int Find(int x){
24     if(x != uf[x])
25         uf[x] = Find(uf[x]);
26     return uf[x];
27 }
28 void tarjan(int u,int ds){
29     vis[u] = true;
30     d[u] = ds;
31     uf[u] = u;
32     int i;
33     for(i = 0; i < g[u].size(); i++){
34         if(!vis[g[u][i].to]) {tarjan(g[u][i].to,ds+g[u][i].w);uf[g[u][i].to] = u;}
35     }
36     for(i = 0; i < q[u].size(); i++)
37     if(vis[q[u][i].to]){
38         ans[q[u][i].id] = d[u]+d[q[u][i].to]-2*d[Find(q[u][i].to)];
39     }
40 }
41 int main(){
42     int i,j,u,v,w;
43     char ch;
44     while(~scanf("%d %d",&n,&m)){
45         for(i = 0; i <= n; i++){
46             g[i].clear();
47             q[i].clear();
48             d[i] = 0;
49             vis[i] = false;
50         }
51         for(i = 0; i < m; i++){
52             scanf("%d %d %d %c",&u,&v,&w,&ch);
53             g[u].push_back((arc){v,w});
54             g[v].push_back((arc){u,w});
55         }
56         scanf("%d",&k);
57         for(i = 0; i < k; i++){
58             scanf("%d %d",&u,&v);
59             q[u].push_back((query){v,i});
60             q[v].push_back((query){u,i});
61         }
62         tarjan(1,0);
63         for(i = 0; i < k; i++)
64             printf("%d\n",ans[i]);
65     }
66     return 0;
67 }