codeforces #368 div 2 B. Bakery (暴力)

题目链接

题意:n个城市,m条双向路,要从k条中选择一个,使得到其他n-k个城市中的某个城市的距离最短。

思路:直接暴力 枚举。1A

 1/* ***********************************************
 2Author :111qqz
 3Created Time :2016年08月20日 星期六 21时02分14秒
 4File Name :code/cf/#368/B.cpp
 5************************************************ */
 6#include <cstdio>
 7#include <cstring>
 8#include <iostream>
 9#include <algorithm>
10#include <vector>
11#include <queue>
12#include <set>
13#include <deque>
14#include <map>
15#include <string>
16#include <cmath>
17#include <cstdlib>
18#include <ctime>
19#define fst first
20#define sec second
21#define lson l,m,rt<<1
22#define rson m+1,r,rt<<1|1
23#define ms(a,x) memset(a,x,sizeof(a))
24typedef long long LL;
25#define pi pair < int ,int >
26#define MP make_pair
27using namespace std;
28const double eps = 1E-8;
29const int dx4[4]={1,0,0,-1};
30const int dy4[4]={0,-1,1,0};
31const int inf = 0x3f3f3f3f;
32const int  N =1E5+7;
33int n,m,k;
34vector <pair <int,LL> >edge[N];
35int b[N];
36bool cangku[N];
37int main()
38{
39	#ifndef  ONLINE_JUDGE 
40	freopen("code/in.txt","r",stdin);
41  #endif
42	ios::sync_with_stdio(false);
43	cin>>n>>m>>k;
44	ms(cangku,false);
45	for ( int i = 1 ; i <= m ; i++)
46	{
47	    int u,v;
48	    LL w;
49	    cin>>u>>v>>w;
50	    edge[u].push_back(make_pair(v,w));
51	    edge[v].push_back(make_pair(u,w));
52	}
53	if (k==0)
54	{
55	    cout<<-1<<endl;
56	    return 0 ;
57	}
58	for ( int i = 1 ; i <= k ; i++)
59	{
60	    cin>>b[i];
61	    cangku[b[i]] = true;
62	}
63	if (k==n)
64	{
65	    cout<<-1<<endl;
66	    return 0;
67	}
68	LL ans = inf;
69	for (int i = 1 ; i <= k ; i++)
70	{
71	    int u = b[i];
72	    int siz = edge[u].size();
73	    for (int j = 0 ; j < siz ; j++)
74	    {
75		int v = edge[u][j].fst;
76		if (cangku[v]) continue;
77		LL w = edge[u][j].sec;
78		ans = min(ans,w);
79	    }
80	}
81	if (ans==inf) ans = -1;
82	cout<<ans<<endl;
83  #ifndef ONLINE_JUDGE  
84  fclose(stdin);
85  #endif
86    return 0;
87}