1 /*
2 无向 最短路
3 spfa
4 */
5 #include<stdio.h>
6 #include<string.h>
7 #include<iostream>
8 #include<algorithm>
9 #include<queue>
10 #include<stack>
11 #define maxn 100005
12 const long long inf = 12345678987654321LL;
13 typedef long long ll;
14 using namespace std;
15 int head[ maxn*2 ],vis[ maxn*2 ],path[ maxn*2 ];
16 ll dis[ maxn*2 ];
17 struct node{
18 int v,next;
19 ll val;
20 }edge[ maxn*2 ];
21 int pindex;
22 void init(){
23 pindex=0;
24 memset(head,-1,sizeof(head));
25 memset(path,-1,sizeof(path));
26 }
27 void addedge(int u,int v,ll val){
28 edge[pindex].v=v;
29 edge[pindex].val=val;
30 edge[pindex].next=head[u];
31 head[u]=pindex++;
32
33 edge[pindex].v=u;
34 edge[pindex].val=val;
35 edge[pindex].next=head[v];
36 head[v]=pindex++;
37 }
38 void output(int n){
39 int id=n;
40 stack<int>s;
41 s.push(n);
42 //for(int i=0;i<n*n*n;i++)cout<<path[i]<<endl;
43 while(path[id]!=-1){
44 s.push(path[id]);//printf("%d ",path[id]);
45 id=path[id];
46 }
47 printf("%d",s.top());s.pop();
48 while(!s.empty()){
49 printf(" %d",s.top());
50 s.pop();
51 }
52 printf("\n");
53 }
54
55 void spfa( int n ){
56 for( int i=1;i<=n;i++ ) dis[ i ]=inf;
57 dis[1]=0;
58 memset( vis,0,sizeof(vis) );
59 vis[1]=1;
60 queue<int>q;
61 q.push(1);
62 while(!q.empty()){
63 int id;
64 id = q.front();
65 q.pop();
66 vis[ id ]=0;
67 for(int i=head[ id ];i!=-1;i=edge[i].next ){
68 int v;
69 v=edge[i].v;
70 if(dis[v]>dis[id]+edge[i].val){
71 dis[v]=dis[id]+edge[i].val;
72 path[v]=id;
73 if(vis[v]==0){
74 vis[v]=1;
75 q.push(v);
76 //path[v]=i;
77 }
78 }
79 }
80 }
81 if(dis[n]>=inf)
82 printf("-1\n");
83 else{
84 output(n);
85 }
86 return ;
87 }
88
89 int main(){
90 int n,m;
91 cin>>n>>m;
92 init();
93 while( m-- ){
94 int a,b;
95 ll c;
96 cin>>a>>b>>c;
97 addedge(a,b,c);
98 }
99 spfa( n );
100 return 0;
101 }
View Code
