POJ 2387 Til the Cows Come Home

 1 #include <iostream>
 2 #include <cstdlib>
 3 #include <cstdio>
 4 #include <algorithm>
 5 #include <vector>
 6 #include <queue>
 7 using namespace std;
 8 #define INF 0xfffffff
 9 #define maxn 1002
10 
11 struct Edge
12 {
13     int e, w;
14 };
15 
16 vector<Edge> G[1002];
17 bool vis[maxn];
18 int dist[maxn], n, m;;
19 
20 void Init()
21 {
22     for(int i=0; i<=n; i++)
23     {
24         G[i].clear();
25         dist[i] = INF;
26         vis[i] = false;
27     }
28 }
29 int Spfa()
30 {
31     Edge P, Pn;
32     queue<Edge> Q;
33     P.e = n, P.w = 0;
34     dist[n] = 0;
35     Q.push(P);
36 
37     while( !Q.empty() )
38     {
39         P = Q.front();
40         Q.pop();
41 
42         vis[P.e] = false;
43         int len = G[P.e].size();
44 
45         for(int i=0; i<len; i++)
46         {
47             Pn = G[P.e][i];
48 
49             if(dist[Pn.e] > dist[P.e] + Pn.w)
50             {
51                 dist[Pn.e] = dist[P.e] + Pn.w;
52 
53                 if( !vis[Pn.e] )
54                 {
55                     Q.push(Pn);
56                     vis[Pn.e] = true;
57                 }
58             }
59         }
60     }
61     return dist[1];
62 }
63 int main()
64 {
65     Edge P;
66 
67     while(cin >> m >> n)
68     {
69         Init();
70         for(int i=0; i<m; i++)
71         {
72             int a, b ,c;
73 
74             scanf("%d%d%d",&a,&b,&c);
75 
76             P.e = b, P.w = c;
77             G[a].push_back(P);
78             P.e = a;
79             G[b].push_back(P);
80         }
81 
82         int ans = Spfa();
83 
84         cout << ans << endl;
85     }
86     return 0;
87 }