最短路~
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#include <cstdio>#include <cstring>#include <utility> #include <queue> using
namespace std; const
int N=20005; const
int INF=9999999; typedef
pair<int,int>seg; priority_queue<seg,vector,greater >q; int
begin,end,d[N],head[N],u[N],v[N],w[N],next[N],n,m,a,b,c; bool
vis[N]; void
build(){ memset(head,-1,sizeof(head)); for(int
e=1;e<=m;e++){ scanf("%d%d%d",&u[e],&v[e],&w[e]); u[e+m]=v[e]; v[e+m]=u[e]; w[e+m]=w[e]; next[e]=head[u[e]]; head[u[e]]=e; next[e+m]=head[u[e+m]]; head[u[e+m]]=e+m; } } void
Dijkstra(int
src){ memset(vis,0,sizeof(vis)); for(int
i=0;i<=n;i++) d[i]=INF; d[src]=0; q.push(make_pair(d[src],src)); while(!q.empty()){ seg now=q.top(); q.pop(); int
x=now.second; if(vis[x]) continue; vis[x]=true; for(int
e=head[x];e!=-1;e=next[e]) if(d[v[e]]>d[x]+w[e]){ d[v[e]]=d[x]+w[e]; q.push(make_pair(d[v[e]],v[e])); } } } int
main(){ while(~scanf("%d%d",&n,&m)){ build(); scanf("%d%d",&begin,&end); if(begin==end){puts("0");continue;} Dijkstra(begin); if(d[end]==INF)puts("-1"); else
printf("%d\n",d[end]); } return
0; } |
原文：http://www.cnblogs.com/forever97/p/3619076.html