POJ 2387

 1 #include<queue>
 2 #include<cstdio>
 3 #include<string>
 4 #include<cstring>
 5 #include<iostream>
 6 #include<algorithm>
 7 #define MAXN 2222
 8 #define INF 0x7fffffff
 9 using namespace std;
10 typedef struct{
11     int to, next, w;
12 }Edge;
13 queue<int>Q;
14 Edge edge[2*MAXN];
15 int head[MAXN/2], vis[MAXN/2], dist[MAXN/2], N, T;
16 void init(){
17     memset(vis, 0, sizeof(vis));
18     for(int i = 1;i < N;i ++) dist[i] = INF;
19     dist[N] = 0;
20 }
21 void addedge(int u, int v, int w, int k){
22     edge[k].to = v;
23     edge[k].w = w;
24     edge[k].next = head[u];
25     head[u] = k++;
26     edge[k].to = u;
27     edge[k].w = w;
28     edge[k].next = head[v];
29     head[v]=k;
30 }
31 void spfa(int s){
32     init();
33     while(!Q.empty()) Q.pop();
34     vis[s] = 1;
35     Q.push(s);
36     while(!Q.empty()){
37         int p = Q.front();
38         Q.pop();
39         vis[p] = 0;
40         for(int i = head[p];~i;i = edge[i].next){
41             int u = edge[i].to;
42             if(dist[u] > dist[p] + edge[i].w){
43                 dist[u] = dist[p] + edge[i].w;
44                 if(!vis[u]){
45                     Q.push(u);
46                     vis[u] = 1;
47                 }
48             }
49         }
50     }
51 }
52 int main(){
53     int u, v, w;
54     /* freopen("in.c", "r", stdin); */
55     while(~scanf("%d%d", &T, &N)){
56         int k = 0;
57         memset(head, -1, sizeof(head));
58         for(int i = 0;i < T;i ++){
59             scanf("%d%d%d", &u, &v, &w);
60             addedge(u, v, w, k);
61             k += 2;
62         }
63         spfa(N);
64         printf("%d\n", dist[1]);
65     }
66     return 0;
67 }