Til the Cows Come Home （最短路模板题）

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cmath>
 4 #include<cstring>
 5 #include<iomanip>
 6 #include<algorithm>
 7 using namespace std;
 8 #define inf 1<<29
 9 int t,n;
10 int cow[1005][1005];
11 int dis[1005];
12 int book[1005];
13 void dijkstra()
14 {
15     memset(book,0,sizeof(book));
16     for(int i=1;i<=n;i++) dis[i]=cow[1][i];
17     dis[1]=0;
18     book[1]=1;
19     for(int i=1;i<=n;i++)
20     {
21         int mina=inf;
22         int k;
23         for(int j=1;j<=n;j++)
24         {
25             if(book[j]==0&&mina>dis[j])
26             {
27                 mina=dis[j];
28                 k=j;
29                 }
30         }
31         book[k]=1;
32         for(int j=1;j<=n;j++)
33         {
34                 if(book[j]==0&&dis[j]>dis[k]+cow[k][j])
35                     dis[j]=dis[k]+cow[k][j];
36             }
37     }
38 }
39 int main()
40 {
41     while(cin>>t>>n){
42     int x,y,z;
43     for(int i=1;i<=n;i++)
44          for(int j=1;j<=n;j++)
45               if(i==j) cow[i][j]=0;
46        else cow[i][j]=inf;
47     for(int i=1;i<=t;i++){
48         cin>>x>>y>>z;
49         if(cow[x][y]>z)
50        cow[x][y]=cow[y][x]=z;
51 
52     }
53     dijkstra();
54     cout<<dis[n]<<endl;}
55         return 0;
56 }

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cmath>
 4 #include<cstring>
 5 #include<iomanip>
 6 #include<algorithm>
 7 using namespace std;
 8 #define inf 1<<29
 9 int t,n;
10 int u[2005],v[2005],w[2005];
11 int dis[1005];
12 int book[1005];
13 int main()
14 {
15     while(cin>>t>>n)
16     {
17         for(int i=1;i<=t;i++)
18             cin>>u[i]>>v[i]>>w[i];
19         for(int i=1;i<=n;i++)
20             dis[i]=inf;
21         dis[1]=0;
22         for(int i=1;i<=n;i++)
23             for(int j=1;j<=t;j++){
24                if(dis[v[j]]>dis[u[j]]+w[j])
25                   dis[v[j]]=dis[u[j]]+w[j];
26                   if(dis[u[j]]>dis[v[j]]+w[j])
27                   dis[u[j]]=dis[v[j]]+w[j];
28 
29             }
30         cout<<dis[n]<<endl;
31 
32     }
33     return 0;
34 }

 1 /*
 2 spfa
 3 Memory 256K
 4 Time   32MS
 5 */
 6 #include <iostream>
 7 #include <queue>
 8 using namespace std;
 9 #define inf 1<<29
10 #define MAXM 4005
11 #define MAXV 1005
12 
13 typedef struct{
14     int a,b,w,next;
15 }Edge;
16 
17 Edge edge[MAXM];
18 int n,m,headlist[MAXV];
19 
20 void spfa(){
21     int i,d[MAXV],v,vis[MAXV];
22     queue <int>q;
23     for(i=2;i<=n;i++){
24         d[i]=inf;
25         vis[i]=0;
26     }
27     d[1]=0;
28     vis[1]=1;
29     q.push(1);
30     while(!q.empty()){
31         v=q.front();q.pop();
32         vis[v]=0;
33 
34         for(i=headlist[v];i!=-1;i=edge[i].next)
35             if(d[v]+edge[i].w<d[edge[i].b]){
36                 d[edge[i].b]=d[v]+edge[i].w;
37                 if(!vis[edge[i].b]){
38                     vis[edge[i].b]=1;
39                     q.push(edge[i].b);
40                 }
41             }
42     }
43     printf("%d\n",d[n]);
44 }
45 
46 int main(){
47     int i,a,b,c;
48     while(~scanf("%d%d",&m,&n)){
49         for(i=1;i<=n;i++) headlist[i]=-1;
50         for(i=1;i<=2*m;i+=2){
51             scanf("%d%d%d",&a,&b,&c);
52             edge[i].a=a;
53             edge[i].b=b;
54             edge[i].w=c;
55             edge[i].next=headlist[a];
56             headlist[a]=i;
57             edge[i+1].a=b;
58             edge[i+1].b=a;
59             edge[i+1].w=c;
60             edge[i+1].next=headlist[b];
61             headlist[b]=i+1;
62         }
63         spfa();
64     }
65     return 0;
66 }