dijkstra模板

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#include<iostream>#include<cstdio>#include<queue>#include<vector>#include<cstring>#include<algorithm>using namespace std;const int maxn=30000+5; struct Edge{int from,to,weight;Edge(int from,int to,int weight):from(from),to(to),weight(weight){}};struct HeapNode{  //prority_queue 中的优先级 int u,dist;   //dist: u点到起点的最短路 ,u: 有向边的终点 HeapNode(int u,int d):u(u),dist(d){}bool operator < (const HeapNode& h) const {return dist>h.dist;}};struct Dijkstra{ //打包在Dijkstra中 int n,m;vector<Edge> edges;vector<int> G[maxn];bool done[maxn];int dist[maxn];int p[maxn];Dijkstra(int n):n(n){for(int i=0;i<n;i++) G[i].clear();edges.clear();}void AddEdge(int from,int to,int weight){edges.push_back(Edge(from,to,weight));m=edges.size();G[from].push_back(m-1);  //保存from出发的边 }void dijkstra(int s){priority_queue<HeapNode> Q;memset(dist,0x7f,sizeof(dist));memset(done,false,sizeof(false));dist[s]=0;Q.push(HeapNode(s,0));while(!Q.empty()){int u=Q.top().u; Q.pop();if(done[u]) continue;done[u]=true;for(int i=0;i<G[u].size();i++){Edge& e=edges[G[u][i]];int v=e.to ,w=e.weight;if(dist[v]>dist[u]+w){dist[v]=dist[u]+w;p[v]=G[u][i];          //记录到各点的最短路径 Q.push(HeapNode(v,dist[v]));}}}}};int main(){int n,m,u,v,w;cin>>n>>m;       //n 点 , m 边 Dijkstra d(n);for(int i=0;i<m;i++){scanf("%d%d%d",&u,&v,&w);d.AddEdge(u,v,w);}d.dijkstra(1);          //1点出发 cout<<d.dist[n]<<endl;  //到n的最短路径 vector<int> ans;  //打印1~n的路径 for(int i=n;i!=1;i=d.edges[d.p[i]].from)ans.push_back(i);for(int i=ans.size()-1;i>=0;i--)cout<<ans[i]<<' ';cout<<1<<endl;cout<<endl;return 0;}

简化版：

#include<iostream>#include<cstdio>#include<queue>#include<vector>#include<cstring>#include<algorithm>using namespace std;const int maxn=100000+5; typedef pair<int,int> pii;struct Edge{int to,weight;Edge(int to,int weight):to(to),weight(weight){}};vector<vector<Edge> > G(maxn);  //更快struct Dijkstra{                //打包在Dijkstra中 int n,m;bool done[maxn];int dist[maxn];int p[maxn];Dijkstra(int n):n(n){for(int i=0;i<n;i++) G[i].clear();}void AddEdge(int from,int to,int weight){G[from].push_back(Edge(to,weight));  //保存from出发的边 }void dijkstra(int s){priority_queue<pii,vector<pii>,greater<pii> > Q;memset(dist,0x7f,sizeof(dist));                  //初始化为无穷大 memset(done,false,sizeof(false));dist[s]=0;Q.push(pii(0,s));      //pii (dist ,u)while(!Q.empty()){int u=Q.top().second; Q.pop();if(done[u]) continue;     //可改为if(dist[u]!=Q.top().first) continue; done[u]=true;            for(int i=0;i<G[u].size();i++){Edge& e=G[u][i];int v=e.to ,w=e.weight;if(dist[v]>dist[u]+w){dist[v]=dist[u]+w;p[v]=u;            //记录到各点的最短路径 Q.push(pii(dist[v],v));}}}}};int main(){int n,m,u,v,w;cin>>n>>m;       //n 点 , m 边 Dijkstra d(n);for(int i=0;i<m;i++){scanf("%d%d%d",&u,&v,&w);d.AddEdge(u,v,w);}d.dijkstra(1);          //1点出发 cout<<d.dist[n]<<endl;  //到n的最短路径 vector<int> ans;for(int i=n;i!=1;i=d.p[i]) ans.push_back(i);ans.push_back(1);for(int i=ans.size()-1;i>=0;i--) cout<<ans[i]<<' ';return 0;}

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