spfa模板
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 #include<iostream> 2 #include<cmath> 3 #include<algorithm> 4 #include<cstring> 5 #include<cstdio> 6 #include<queue> 7 #define inf 2147483647 8 using namespace std; 9 struct data 10 { 11 int from,to,next,w; 12 data(){from=-1,to=-1,next=-1,w=-1;} 13 }e[2000]; 14 int n,m; 15 int head[2000]; 16 int d[2000],p[2000],sum[2000]; 17 bool vis[2000]; 18 int cnt=0; 19 void add(int u,int v,int w){e[cnt].from=u,e[cnt].to=v;e[cnt].next=head[u],head[u]=cnt,e[cnt].w=w,cnt++;} 20 bool spfa(int s) 21 { 22 queue<int> q; 23 for(int i=1;i<=n;i++) d[i]=inf; 24 q.push(s); 25 d[s]=0; 26 memset(vis,0,sizeof(vis)); 27 vis[s]=1; 28 while(!q.empty()) 29 { 30 int x=q.front(); 31 q.pop(); 32 vis[x]=0; 33 for(int i=head[x];i>=0;i=e[i].next) 34 { 35 if(d[e[i].from]<inf&&d[e[i].to]>d[e[i].from]+e[i].w) 36 { 37 d[e[i].to]=d[e[i].from]+e[i].w; 38 p[e[i].to]=i; 39 if(!vis[e[i].to]){q.push(e[i].to);vis[e[i].to]=1;if(++sum[e[i].to]>n) return false;} 40 } 41 } 42 } 43 return true; 44 } 45 int main() 46 { 47 memset(head,-1,sizeof(head)); 48 scanf("%d%d",&n,&m); 49 for(int i=1;i<=m;i++) 50 { 51 int u,v,w; 52 scanf("%d%d%d",&u,&v,&w); 53 add(u,v,w); 54 add(v,u,w); 55 } 56 int s,t; 57 scanf("%d%d",&s,&t); 58 spfa(s); 59 cout<<d[t]; 60 }
O(∩_∩)O~ (*^__^*) 嘻嘻…… O(∩_∩)O哈哈~