AOJ-2249 Road Construction(最短路）

 1 #include <iostream>
 2 #include <vector>
 3 #include <queue>
 4 #include <cstdio>
 5 using namespace std;
 6 
 7 const int maxn = 10010;
 8 const int INF = 1<<29;
 9 struct edge {
10     int to,cost,distance;
11     edge(){}
12     edge( int x,int y,int z ) {
13         to=x;
14         distance=y;
15         cost=z;
16     }
17 };
18 
19 typedef pair<int,int>P;
20 vector<edge>G[maxn];
21 int d[maxn];
22 int N;
23 
24 void dijkstra(int s) {
25     priority_queue<P,vector<P>,greater<P> >que;
26     for(int i=1;i<=N;i++) d[i]=INF;
27     d[s]=0;
28     que.push(P(0,s));
29 
30     while(!que.empty()) {
31         P p=que.top(); que.pop();
32         int v=p.second;
33         if(d[v]<p.first) continue;
34         for(int i=0;i<G[v].size();i++) {
35             edge e=G[v][i];
36             if(d[e.to]>d[v]+e.distance) {
37                 d[e.to]=d[v]+e.distance;
38                 que.push(P(d[e.to],e.to));
39             }
40         }
41     }
42 }
43 
44 int main()
45 {
46    //freopen("a.txt","r",stdin);
47     int M;
48     while(~scanf("%d%d",&N,&M)&&(N+M)) {
49         for(int i=1;i<=N;i++) G[i].clear();
50         int a,b,c,v;
51         for(int i=0;i<M;i++) {
52             scanf("%d%d%d%d",&a,&b,&c,&v);
53           //  printf("%d %d %d %d\n",a,b,c,v);
54             G[a].push_back(edge(b,c,v));
55             G[b].push_back(edge(a,c,v));
56         }
57         dijkstra(1);
58        // for(int i=1;i<=N;i++) printf("%d\n",d[i]);
59         int sum=0;
60         for(int i=2;i<=N;++i) {
61             int min_cost=INF;
62             for(int j=0;j<G[i].size();++j) {
63                 edge &e=G[i][j];
64                // printf("%d %d %d\n",e.to,d[e.to],e.distance);
65                 if(d[e.to]+e.distance==d[i]&&e.cost<min_cost)
66                 {
67                     min_cost=e.cost;
68                 }
69             }
70             sum+=min_cost;
71         }
72         printf("%d\n",sum);
73     }
74     return 0;
75 }