uva 10986 Sending email (spfa)

 1#include <cstdio>
 2#include <cstring>
 3#include <iostream>
 4#include <algorithm>
 5#include <vector>
 6#include <queue>
 7#include <set>
 8#include <map>
 9#include <string>
10#include <cmath>
11#include <cstdlib>
12#include <ctime>
13#define fst first
14#define sec second
15#define lson l,m,rt<<1
16#define rson m+1,r,rt<<1|1
17#define ms(a,x) memset(a,x,sizeof(a))
18typedef long long LL;
19#define pi pair < int ,int >
20#define MP make_pair

1using namespace std;
2const double eps = 1E-8;
3const int dx4[4]={1,0,0,-1};
4const int dy4[4]={0,-1,1,0};
5const int inf = 0x3f3f3f3f;
6const int N=2E4+7;
7int n,m;
8int S,T;
9vector < pi > edge[N];

 1int d[N];
 2bool inq[N];
 3bool spfa( int s,int t)
 4{
 5    ms(d,0x3f);
 6    ms(inq,false);
 7    queue<int>q;
 8    q.push(s);
 9    inq[s] = true;
10    d[s] = 0;

1    while (!q.empty())
2    {
3	int u = q.front();
4	q.pop();
5	inq[u] = false;

 1	for ( int i = 0 ; i < siz ; i++)
 2	{
 3	    int v = edge[u][i].fst;
 4	    if (d[v]>d[u] + edge[u][i].sec)
 5	    {
 6		d[v] = d[u] + edge[u][i].sec;
 7		if (inq[v]) continue;
 8		inq[v] = true;
 9		q.push(v);
10	    }
11	}
12    }
13    return d[t]!=inf;
14}
15int main()
16{
17	#ifndef  ONLINE_JUDGE 
18	freopen("code/in.txt","r",stdin);
19  #endif
20	ios::sync_with_stdio(false);
21	int TT;
22	cin>>TT;
23	int cas = 0 ;
24	while (TT--)
25	{
26	    cin>>n>>m>>S>>T;
27	    for ( int i = 0 ; i <= n ; i++) edge[i].clear();
28	    for ( int i = 1 ; i <= m ; i++)
29	    {
30		int u,v,w;
31		cin>>u>>v>>w;
32		edge[u].push_back(make_pair(v,w));
33		edge[v].push_back(make_pair(u,w));
34	    }

1	    if (spfa(S,T))
2	    {
3		printf("Case #%d: %d\n",++cas,d[T]);
4	    }
5	    else
6	    {
7		printf("Case #%d: unreachable\n",++cas);
8	    }

1  #ifndef ONLINE_JUDGE  
2  fclose(stdin);
3  #endif
4    return 0;
5}