BZOJ3394: [Usaco2009 Jan]Best Spot 最佳牧场

 1 #include<cstdio>
 2 #include<cstdlib>
 3 #include<cmath>
 4 #include<cstring>
 5 #include<algorithm>
 6 #include<iostream>
 7 #include<vector>
 8 #include<map>
 9 #include<set>
10 #include<queue>
11 #include<string>
12 #define inf 1000000000
13 #define maxn 1000
14 #define maxm 100000
15 #define eps 1e-10
16 #define ll long long
17 #define pa pair<int,int>
18 #define for0(i,n) for(int i=0;i<=(n);i++)
19 #define for1(i,n) for(int i=1;i<=(n);i++)
20 #define for2(i,x,y) for(int i=(x);i<=(y);i++)
21 #define for3(i,x,y) for(int i=(x);i>=(y);i--)
22 #define mod 1000000007
23 using namespace std;
24 inline int read()
25 {
26     int x=0,f=1;char ch=getchar();
27     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
28     while(ch>=‘0‘&&ch<=‘9‘){x=10*x+ch-‘0‘;ch=getchar();}
29     return x*f;
30 }
31 struct edge{int go,next,w;}e[2*maxm];
32 int n,m,k,s,tot,a[maxn],b[maxn],q[maxn],d[maxn][maxn],head[maxn];
33 bool v[maxn];
34 void ins(int x,int y,int z)
35 {
36     e[++tot].go=y;e[tot].w=z;e[tot].next=head[x];head[x]=tot;
37 }
38 void insert(int x,int y,int z)
39 {
40     ins(x,y,z);ins(y,x,z);
41 }
42 void spfa(int s)
43 {
44     for(int i=1;i<=n;++i) d[s][i]=inf;
45     memset(v,0,sizeof(v));
46     int l=0,r=1,x,y;q[1]=s;d[s][s]=0;
47     while(l!=r)
48     {
49         x=q[++l];if(l==maxn-1)l=0;v[x]=0;
50         for(int i=head[x];i;i=e[i].next)
51          if(d[s][x]+e[i].w<d[s][y=e[i].go])
52          {
53              d[s][y]=d[s][x]+e[i].w;
54              if(!v[y]){v[y]=1;q[++r]=y;if(r==maxn-1)r=0;}
55          }
56     }
57 }
58 int main()
59 {
60     freopen("input.txt","r",stdin);
61     freopen("output.txt","w",stdout);
62     n=read();k=read();m=read();
63     for1(i,k)a[i]=read();
64     for1(i,m)
65     {
66         int x=read(),y=read(),z=read();
67         insert(x,y,z);
68     }
69     for1(i,n)spfa(i);
70     int ans=1;
71     for1(i,n)
72     {
73         for1(j,k)b[i]+=d[i][a[j]];
74         if(b[i]<b[ans])ans=i;
75     }
76     printf("%d\n",ans);
77     return 0;
78 }